Route Summarization [7:62347]
Hello All, I have a question about route summarization. I was reading over the material from Cisco on the matter, I was wondering; or actually assuming. If you want to have route summarization in place to you need continuos network numbers? I know that the docs. said you would send a network address upstream that would reflect the bit that are common to all networks thus decreasing the size of the routing tables which is great. But what if someone else owned a network block on the net that was randomly missing from your group? Again, I can only assume that you must have all continuous networks. Is this correct, or am I missing something? Thank you all, Steven Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=62347t=62347 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Route Summarization [7:62347]
Steven Aiello wrote: Hello All, I have a question about route summarization. I was reading over the material from Cisco on the matter, I was wondering; or actually assuming. If you want to have route summarization in place to you need continuos network numbers? I know that the docs. said you would send a network address upstream that would reflect the bit that are common to all networks thus decreasing the size of the routing tables which is great. But what if someone else owned a network block on the net that was randomly missing from your group? Again, I can only assume that you must have all continuous networks. Is this correct, or am I missing something? Thank you all, Steven More or less I think that's true. But in the example where someone else has a block of addresses from the middle of an otherwise contiguous block, that can be accommodated. In most instances, the most specific match is used. So as long as that rouge block was being advertised with a more specific mask, there shouldn't be any problems. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=62353t=62347 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Route Summarization [7:62347]
Steve The missing one if advertised with smaller block will take effect. Rgds, Kiran From: Steven Aiello Reply-To: Steven Aiello To: [EMAIL PROTECTED] Subject: Route Summarization [7:62347] Date: Mon, 3 Feb 2003 14:15:20 GMT Hello All, I have a question about route summarization. I was reading over the material from Cisco on the matter, I was wondering; or actually assuming. If you want to have route summarization in place to you need continuos network numbers? I know that the docs. said you would send a network address upstream that would reflect the bit that are common to all networks thus decreasing the size of the routing tables which is great. But what if someone else owned a network block on the net that was randomly missing from your group? Again, I can only assume that you must have all continuous networks. Is this correct, or am I missing something? Thank you all, Steven _ Tired of spam? Get advanced junk mail protection with MSN 8. http://join.msn.com/?page=features/junkmail Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=62422t=62347 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF External Summarization Problem [7:50260]
Why can't you use the summary-address on the ASBRs. Is there some restriction? Jay Greenberg wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hello group, I seem to have a problem with OSPF external LSA summarization. I have an Ethernet segment in area 4. There are 2 ASBRs (RAS Gear), and 1 ABR (the router connected to my backbone). Suppose for now, that ASBR1 is injecting 192.168.0.1/32 into OSPF as an E2 LSA, and ASBR2 is injecting 192.168.0.128/25 into OSPF as an E2 LSA. I would like the other areas to just understand that 192.168.0.0/24 is reachable via the area 4 ABR, however, #area 4 range 192.168.0.0 255.255.255.0 will not work, because it will not summarize external routes, and I cannot use summary-address (or can I?) on the ABR, because it is only supposed to be used by ASBRs. My question is: How can I get the ABR to summarise the /24? Jay Greenberg Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=51429t=50260 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF External Summarization Problem [7:50260]
I'm just going to assume you're running standard areas everywhere. While it is supposedly possible to summarize on the ABR with summary-address, I prefer to use summary-address on the ASBR that is doing the redistribution. area range is used for summarizing that area's networks into the backbone area as such: area4_abr(config-router)#area 0 range 192.168.0.0 255.255.255.0 (summarizes from area4 into area0) foo_abr(config-router)#area foo range 192.168.0.0 255.255.255.0 will summarize 192.168.0.0/24 into area 'foo' hth, -Mark Jay Greenberg wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hello group, I seem to have a problem with OSPF external LSA summarization. I have an Ethernet segment in area 4. There are 2 ASBRs (RAS Gear), and 1 ABR (the router connected to my backbone). Suppose for now, that ASBR1 is injecting 192.168.0.1/32 into OSPF as an E2 LSA, and ASBR2 is injecting 192.168.0.128/25 into OSPF as an E2 LSA. I would like the other areas to just understand that 192.168.0.0/24 is reachable via the area 4 ABR, however, #area 4 range 192.168.0.0 255.255.255.0 will not work, because it will not summarize external routes, and I cannot use summary-address (or can I?) on the ABR, because it is only supposed to be used by ASBRs. My question is: How can I get the ABR to summarise the /24? Jay Greenberg Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=50377t=50260 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF External Summarization Problem [7:50260]
No, I just tested this and summary-address on the ABR did not summarize the external LSAs, because the redistribution did not occur on the ABR. On Thu, 2002-08-01 at 10:10, Mark Turpin wrote: I'm just going to assume you're running standard areas everywhere. While it is supposedly possible to summarize on the ABR with summary-address, I prefer to use summary-address on the ASBR that is doing the redistribution. area range is used for summarizing that area's networks into the backbone area as such: area4_abr(config-router)#area 0 range 192.168.0.0 255.255.255.0 (summarizes from area4 into area0) foo_abr(config-router)#area foo range 192.168.0.0 255.255.255.0 will summarize 192.168.0.0/24 into area 'foo' hth, -Mark Jay Greenberg wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hello group, I seem to have a problem with OSPF external LSA summarization. I have an Ethernet segment in area 4. There are 2 ASBRs (RAS Gear), and 1 ABR (the router connected to my backbone). Suppose for now, that ASBR1 is injecting 192.168.0.1/32 into OSPF as an E2 LSA, and ASBR2 is injecting 192.168.0.128/25 into OSPF as an E2 LSA. I would like the other areas to just understand that 192.168.0.0/24 is reachable via the area 4 ABR, however, #area 4 range 192.168.0.0 255.255.255.0 will not work, because it will not summarize external routes, and I cannot use summary-address (or can I?) on the ABR, because it is only supposed to be used by ASBRs. My question is: How can I get the ABR to summarise the /24? Jay Greenberg -- Jason Greenberg, CCNP Network Administrator Execulink, Inc. [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=50391t=50260 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF External Summarization Problem [7:50260]
Type 5 LSA's flood ospf domain wide and are not processed by ABR's. The only opportunity to summarize or otherwise modify them is at the point of injection into the OSPF domain (which by definition occurs on an ASBR) The only small exception to this is for type 7 to type 5 conversions which can be summarized or filtered by the NSSA ABR that performs the translation from 7 to 5. At 03:39 PM 8/1/2002 +, Jason Greenberg wrote: No, I just tested this and summary-address on the ABR did not summarize the external LSAs, because the redistribution did not occur on the ABR. On Thu, 2002-08-01 at 10:10, Mark Turpin wrote: I'm just going to assume you're running standard areas everywhere. While it is supposedly possible to summarize on the ABR with summary-address, I prefer to use summary-address on the ASBR that is doing the redistribution. area range is used for summarizing that area's networks into the backbone area as such: area4_abr(config-router)#area 0 range 192.168.0.0 255.255.255.0 (summarizes from area4 into area0) foo_abr(config-router)#area foo range 192.168.0.0 255.255.255.0 will summarize 192.168.0.0/24 into area 'foo' hth, -Mark Jay Greenberg wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hello group, I seem to have a problem with OSPF external LSA summarization. I have an Ethernet segment in area 4. There are 2 ASBRs (RAS Gear), and 1 ABR (the router connected to my backbone). Suppose for now, that ASBR1 is injecting 192.168.0.1/32 into OSPF as an E2 LSA, and ASBR2 is injecting 192.168.0.128/25 into OSPF as an E2 LSA. I would like the other areas to just understand that 192.168.0.0/24 is reachable via the area 4 ABR, however, #area 4 range 192.168.0.0 255.255.255.0 will not work, because it will not summarize external routes, and I cannot use summary-address (or can I?) on the ABR, because it is only supposed to be used by ASBRs. My question is: How can I get the ABR to summarise the /24? Jay Greenberg -- Jason Greenberg, CCNP Network Administrator Execulink, Inc. [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=50425t=50260 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF External Summarization Problem [7:50260]
Hello group, I seem to have a problem with OSPF external LSA summarization. I have an Ethernet segment in area 4. There are 2 ASBRs (RAS Gear), and 1 ABR (the router connected to my backbone). Suppose for now, that ASBR1 is injecting 192.168.0.1/32 into OSPF as an E2 LSA, and ASBR2 is injecting 192.168.0.128/25 into OSPF as an E2 LSA. I would like the other areas to just understand that 192.168.0.0/24 is reachable via the area 4 ABR, however, #area 4 range 192.168.0.0 255.255.255.0 will not work, because it will not summarize external routes, and I cannot use summary-address (or can I?) on the ABR, because it is only supposed to be used by ASBRs. My question is: How can I get the ABR to summarise the /24? Jay Greenberg Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=50260t=50260 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
I don't think its unreachable. Cisco tests OTOH Most people use the 2^n-2 rule for determining the number of available/usable networks. The -2 is there because of the need to remove the network and broadcast subnet. I don't write the rules, I just question them :) I agree with you 100% that there are 16 subnets. I was trying to point out that those that we bringing up the fact that in the old world only 14 were available were not reading the question correctly. It didn't ask for usability, it asked for quantity. As I am sure you are aware, as you take more and more Cisco tests, it becomes important to clarify what they are actually asking for, not what would make sense for them to ask for... Its also important to note that IP subnet zero is still needed on Cisco eq for it to route/subnet properly, they just enabled it by default now... Thanks Larry -Original Message- From: Chuck [mailto:[EMAIL PROTECTED]] Sent: Friday, July 12, 2002 3:13 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] ah, but that is old world classful thinking. as per RFC 1812, effectively there is no such thing as subnet zero any longer. per that RFC, all routers SHOULD route to any address in the form of network:host, or network:subnet:host. subnet zero is a holdover from the old world. it is there because of the concern that there is still so much old world equipment out there. RFC 1812 is dated June 1995, and one wonders how long it takes in practical terms for all manufacturers and all software stack writers to get all their stuff up to standard.. not to mention how long it takes for the old stuff to be removed from production. hhhm. a brief look through ARIN seems to indicate that assignments are not made out of subnet zero space but that is still a different question. a summarization produces a single route where several existed before. if you see a summary 192.1.0.0/16, why would you think that 192.1.0.0/24 is unreachable? Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Just to jump in late on this, but... The question doesn't ask how many of those class C are usable, which would be dependant on subnet O, but instead the question was how many you would be able to summarize. A /20 would in fact summarize 16, 14 of which are useable without subnet zero... Thanks Larry -Original Message- From: Dain Deutschman [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 10, 2002 4:05 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Hey everyone, Thanks for all of your help. I have decided that 16 must be correct since it makes perfect sense and most of you back that up as well. I think the test question was just plain wrong. Anyway...I passed the CCNP Routing exam today so I'm pretty happy. : ) Groupstudy is a great learning resource. Thanks everyone. Dain. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48734t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Larry, I'm only beating this dead horse for the CCNA/ beginner types on the list, who really do need to learn to distinguish between the function of a route summary versus the practicality of subnetting classful networks such that subnet zero becomes an issue. while I wouldn't bet the house on it, I suspect that even on Cisco tests, there would not be question about summarization where the subnet zero, all ones subnet count ( 2^n-2) would be the right answer. ( although I would not be surprised to see this in some of the study materials, given what I know about how quality control is valued with certain publishers. ) I was more concerned that it became a point of disagreement during the course of this thread, indicating that there were some who did not understand the why of things. Is ip subnet-zero enabled by default now? Which IOS release? Last I checked ( command reference for 12.2 ) the default was still disabled IP classless is now enabled by default, but not subnet-zero. this could have changed. the docs on CCO tend to be a bit behind reality. Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I don't think its unreachable. Cisco tests OTOH Most people use the 2^n-2 rule for determining the number of available/usable networks. The -2 is there because of the need to remove the network and broadcast subnet. I don't write the rules, I just question them :) I agree with you 100% that there are 16 subnets. I was trying to point out that those that we bringing up the fact that in the old world only 14 were available were not reading the question correctly. It didn't ask for usability, it asked for quantity. As I am sure you are aware, as you take more and more Cisco tests, it becomes important to clarify what they are actually asking for, not what would make sense for them to ask for... Its also important to note that IP subnet zero is still needed on Cisco eq for it to route/subnet properly, they just enabled it by default now... Thanks Larry -Original Message- From: Chuck [mailto:[EMAIL PROTECTED]] Sent: Friday, July 12, 2002 3:13 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] ah, but that is old world classful thinking. as per RFC 1812, effectively there is no such thing as subnet zero any longer. per that RFC, all routers SHOULD route to any address in the form of network:host, or network:subnet:host. subnet zero is a holdover from the old world. it is there because of the concern that there is still so much old world equipment out there. RFC 1812 is dated June 1995, and one wonders how long it takes in practical terms for all manufacturers and all software stack writers to get all their stuff up to standard.. not to mention how long it takes for the old stuff to be removed from production. hhhm. a brief look through ARIN seems to indicate that assignments are not made out of subnet zero space but that is still a different question. a summarization produces a single route where several existed before. if you see a summary 192.1.0.0/16, why would you think that 192.1.0.0/24 is unreachable? Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Just to jump in late on this, but... The question doesn't ask how many of those class C are usable, which would be dependant on subnet O, but instead the question was how many you would be able to summarize. A /20 would in fact summarize 16, 14 of which are useable without subnet zero... Thanks Larry -Original Message- From: Dain Deutschman [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 10, 2002 4:05 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Hey everyone, Thanks for all of your help. I have decided that 16 must be correct since it makes perfect sense and most of you back that up as well. I think the test question was just plain wrong. Anyway...I passed the CCNP Routing exam today so I'm pretty happy. : ) Groupstudy is a great learning resource. Thanks everyone. Dain. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48737t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
By all means beat the dead horse. I would rather people learn the how's and why's , instead of just a memorization of what to answer. I looked up the 12.1 reference and it says that ip subnet-zero is enabled. Hopefully I have inserted enough padding for the url. (watch the wrap ) http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/ip_r /iprprt1/1rdipadr.htm#1020464 Having not worked with 12.2 I cant vouch that it has not be disabled, I just don't think it would. Call it an assumption, although I am aware of what assuming does :) The doc's also show, although less clear, that it appears to be enabled by default in 12.2. I don't have first hand knowledge of 12.2 so I am left to just trust the doc's... http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr _c/ipcprt1/1cfipadr.htm#1001056 I suspect that if Cisco was to test you on the 2^n vs. 2^n-2, that only one of them would be available. Thanks Larry -Original Message- From: Chuck [mailto:[EMAIL PROTECTED]] Sent: Saturday, July 13, 2002 1:28 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Larry, I'm only beating this dead horse for the CCNA/ beginner types on the list, who really do need to learn to distinguish between the function of a route summary versus the practicality of subnetting classful networks such that subnet zero becomes an issue. while I wouldn't bet the house on it, I suspect that even on Cisco tests, there would not be question about summarization where the subnet zero, all ones subnet count ( 2^n-2) would be the right answer. ( although I would not be surprised to see this in some of the study materials, given what I know about how quality control is valued with certain publishers. ) I was more concerned that it became a point of disagreement during the course of this thread, indicating that there were some who did not understand the why of things. Is ip subnet-zero enabled by default now? Which IOS release? Last I checked ( command reference for 12.2 ) the default was still disabled IP classless is now enabled by default, but not subnet-zero. this could have changed. the docs on CCO tend to be a bit behind reality. Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I don't think its unreachable. Cisco tests OTOH Most people use the 2^n-2 rule for determining the number of available/usable networks. The -2 is there because of the need to remove the network and broadcast subnet. I don't write the rules, I just question them :) I agree with you 100% that there are 16 subnets. I was trying to point out that those that we bringing up the fact that in the old world only 14 were available were not reading the question correctly. It didn't ask for usability, it asked for quantity. As I am sure you are aware, as you take more and more Cisco tests, it becomes important to clarify what they are actually asking for, not what would make sense for them to ask for... Its also important to note that IP subnet zero is still needed on Cisco eq for it to route/subnet properly, they just enabled it by default now... Thanks Larry -Original Message- From: Chuck [mailto:[EMAIL PROTECTED]] Sent: Friday, July 12, 2002 3:13 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] ah, but that is old world classful thinking. as per RFC 1812, effectively there is no such thing as subnet zero any longer. per that RFC, all routers SHOULD route to any address in the form of network:host, or network:subnet:host. subnet zero is a holdover from the old world. it is there because of the concern that there is still so much old world equipment out there. RFC 1812 is dated June 1995, and one wonders how long it takes in practical terms for all manufacturers and all software stack writers to get all their stuff up to standard.. not to mention how long it takes for the old stuff to be removed from production. hhhm. a brief look through ARIN seems to indicate that assignments are not made out of subnet zero space but that is still a different question. a summarization produces a single route where several existed before. if you see a summary 192.1.0.0/16, why would you think that 192.1.0.0/24 is unreachable? Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Just to jump in late on this, but... The question doesn't ask how many of those class C are usable, which would be dependant on subnet O, but instead the question was how many you would be able to summarize. A /20 would in fact summarize 16, 14 of which are useable without subnet zero... Thanks Larry -Original Message- From: Dain Deutschman [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 10, 2002 4:05 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:
RE: Class C summarization question [7:48367]
Just to jump in late on this, but... The question doesn't ask how many of those class C are usable, which would be dependant on subnet O, but instead the question was how many you would be able to summarize. A /20 would in fact summarize 16, 14 of which are useable without subnet zero... Thanks Larry -Original Message- From: Dain Deutschman [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 10, 2002 4:05 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Hey everyone, Thanks for all of your help. I have decided that 16 must be correct since it makes perfect sense and most of you back that up as well. I think the test question was just plain wrong. Anyway...I passed the CCNP Routing exam today so I'm pretty happy. : ) Groupstudy is a great learning resource. Thanks everyone. Dain. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48688t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
ah, but that is old world classful thinking. as per RFC 1812, effectively there is no such thing as subnet zero any longer. per that RFC, all routers SHOULD route to any address in the form of network:host, or network:subnet:host. subnet zero is a holdover from the old world. it is there because of the concern that there is still so much old world equipment out there. RFC 1812 is dated June 1995, and one wonders how long it takes in practical terms for all manufacturers and all software stack writers to get all their stuff up to standard.. not to mention how long it takes for the old stuff to be removed from production. hhhm. a brief look through ARIN seems to indicate that assignments are not made out of subnet zero space but that is still a different question. a summarization produces a single route where several existed before. if you see a summary 192.1.0.0/16, why would you think that 192.1.0.0/24 is unreachable? Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Just to jump in late on this, but... The question doesn't ask how many of those class C are usable, which would be dependant on subnet O, but instead the question was how many you would be able to summarize. A /20 would in fact summarize 16, 14 of which are useable without subnet zero... Thanks Larry -Original Message- From: Dain Deutschman [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 10, 2002 4:05 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Hey everyone, Thanks for all of your help. I have decided that 16 must be correct since it makes perfect sense and most of you back that up as well. I think the test question was just plain wrong. Anyway...I passed the CCNP Routing exam today so I'm pretty happy. : ) Groupstudy is a great learning resource. Thanks everyone. Dain. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48693t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Hey everyone, Thanks for all of your help. I have decided that 16 must be correct since it makes perfect sense and most of you back that up as well. I think the test question was just plain wrong. Anyway...I passed the CCNP Routing exam today so I'm pretty happy. : ) Groupstudy is a great learning resource. Thanks everyone. Dain. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48536t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
For a Cisco test the actuall answer would be 14. Unfortunately, for us, they don't take subnet zero into consideration for tests. So, if you have that question on the test answer 14, for the real-world it's 16. In other words, the answer to the BSCN question is wrong. Carl Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48379t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48389t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Firstly, 2 to the power of 4 is 16 (2x2x2x2). Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48393t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Bob Timmons wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I agree. A /20 can summarize 16 - /24 networks. AFAIK this is separate from zero-subnets and subnetting. Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48396t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
One of the choices in the question was 16but 14 was not a choice. Could it be that since 14 was not a choice that 8 was the closest thing since 16 is possibly wrong because of the 0 subnet? This seems a little off the wall to me butsometimes those cisco questions are off the wall. Dain. Bob Timmons wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Firstly, 2 to the power of 4 is 16 (2x2x2x2). Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48398t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
Bob, I would have to agree. With CIDR, in most cases you will get 16 usable subnets and 2 unusable addresses (the network and the broadcast). ex. 192.168.96.0 255.255.240.0 192.168.96.1 -- 192.168.111.254 all usable 192.168.96.0 network 192.168.111.255 broadcast I could see the question possibly not wanting the zero subnet if you used the following: 192.168.0.0 -- 192.168.15.255 where the 192.168.0.X network might be classified as unusable. This would give you 15 usable subnets... Tim CCIE 9015 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Bob Timmons Sent: Tuesday, July 09, 2002 7:28 AM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Firstly, 2 to the power of 4 is 16 (2x2x2x2). Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48403t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
If the choices are either 8 or 16, I'd definitely go with 16. 192.168.0.0/20 would be (for example): 192.168.0.1 to 192.168.15.254 Which is 16 total subnets. One of the choices in the question was 16but 14 was not a choice. Could it be that since 14 was not a choice that 8 was the closest thing since 16 is possibly wrong because of the 0 subnet? This seems a little off the wall to me butsometimes those cisco questions are off the wall. Dain. Bob Timmons wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Firstly, 2 to the power of 4 is 16 (2x2x2x2). Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48404t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
I was thinking of subnetting and not summarization, it was a little late. 16, not 14, is correct. Carl Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48405t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Dain Deutschman wrote: One of the choices in the question was 16but 14 was not a choice. Could it be that since 14 was not a choice that 8 was the closest thing since 16 is possibly wrong because of the 0 subnet? This seems a little off the wall to me butsometimes those cisco questions are off the wall. Dain. But couldn't you use that same logic and say 16 was the closest since 8 is wrong and 14 wasn't an answer? I still say 16 is the answer. Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48406t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
ah come on, guys, now you're all trying to outsmart yourselves. nothing in the RFC's regarding CIDR / summarization mentions a subnet zero why should it? that would defeat the purpose of CIDR/summarization. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... One of the choices in the question was 16but 14 was not a choice. Could it be that since 14 was not a choice that 8 was the closest thing since 16 is possibly wrong because of the 0 subnet? This seems a little off the wall to me butsometimes those cisco questions are off the wall. Dain. Bob Timmons wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Firstly, 2 to the power of 4 is 16 (2x2x2x2). Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48413t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Dain, Just out of curiosity, who was the author of the test question? When I was studying for my CCNP I ran into several poorly written questions and others, like this one, that were just plain wrong. Also, are the people that think that 2 to the power of 4 equals 8 the same people that write to this list asking what they should study since they failed the CCNA on the first and second attempts? -- Brad A. Nixon CCNP, CCDA, MCP, CCSA Nothing is fool proof to a sufficiently talented fool. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48414t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
Ok I guess I deserved that. I was thinking of the 4th bit has a value of 8 in my head and forgot to add the values of the rest of the bits. -Original Message- From: Michael L. Williams [mailto:[EMAIL PROTECTED]] Sent: Monday, July 08, 2002 10:01 PM To: Andy Hoang; [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Wow. According to my binary math, 4 bits = 16 combinations. 1 bit = 2 combinations (2^1 = 2) 2 bits = 4 combinations (2^2 = 4) 3 bits = 8 combinations (2^3 = 8) 4 bits = 16 combinations (2^4 = 16) Now. when converting from binary to decimal, the 4th bit (from the right) has a (decimal) value of 8 (2^[4-1]), but of course when you add the values of the bits from 4 down, you get 8+4+2+1 = 15 (thus giving 16 combinations, 0 through 15) (Too all that have read my posts in the past, now you know why I bitch up a storm when I hear someone encourage someone else to memorize subnetting charts and bitswapping charts instead of taking an hour and learning how binary actually works... geez) Mike W. - Original Message - From: Andy Hoang To: Michael L. Williams ; Sent: Monday, July 08, 2002 10:51 PM Subject: RE: Class C summarization question [7:48367] I would say 8 is correct. 4 bits make 8 combinations. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Monday, July 08, 2002 8:15 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48458t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Class C summarization question [7:48367]
I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48367t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48368t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
16 is the correct answer. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Dain Deutschman Sent: Monday, July 08, 2002 7:51 PM To: [EMAIL PROTECTED] Subject: Class C summarization question [7:48367] I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48369t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Thanks...it's good to know I'm not completely losing my mind. : ) Dain Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48370t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
I would say 8 is correct. 4 bits make 8 combinations. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Monday, July 08, 2002 8:15 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48371t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Actually...4 bits makes 16 combinations( 2 to the power of 4 = 16 ) ( 4 positions with 2 possibilities per bit position ) Dain Andy Hoang wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I would say 8 is correct. 4 bits make 8 combinations. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Monday, July 08, 2002 8:15 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48372t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Wow. According to my binary math, 4 bits = 16 combinations. 1 bit = 2 combinations (2^1 = 2) 2 bits = 4 combinations (2^2 = 4) 3 bits = 8 combinations (2^3 = 8) 4 bits = 16 combinations (2^4 = 16) Now. when converting from binary to decimal, the 4th bit (from the right) has a (decimal) value of 8 (2^[4-1]), but of course when you add the values of the bits from 4 down, you get 8+4+2+1 = 15 (thus giving 16 combinations, 0 through 15) (Too all that have read my posts in the past, now you know why I bitch up a storm when I hear someone encourage someone else to memorize subnetting charts and bitswapping charts instead of taking an hour and learning how binary actually works... geez) Mike W. - Original Message - From: Andy Hoang To: Michael L. Williams ; Sent: Monday, July 08, 2002 10:51 PM Subject: RE: Class C summarization question [7:48367] I would say 8 is correct. 4 bits make 8 combinations. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Monday, July 08, 2002 8:15 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48374t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
FYI for who ever wants to knowA great website for learning subnetting ( actually learning the binary whys and hows instead of shortcuts ) is www.learntosubnet.com There are some great free resources...and very good explanations for those who are just starting to learn it. Dain Michael L. Williams wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Wow. According to my binary math, 4 bits = 16 combinations. 1 bit = 2 combinations (2^1 = 2) 2 bits = 4 combinations (2^2 = 4) 3 bits = 8 combinations (2^3 = 8) 4 bits = 16 combinations (2^4 = 16) Now. when converting from binary to decimal, the 4th bit (from the right) has a (decimal) value of 8 (2^[4-1]), but of course when you add the values of the bits from 4 down, you get 8+4+2+1 = 15 (thus giving 16 combinations, 0 through 15) (Too all that have read my posts in the past, now you know why I bitch up a storm when I hear someone encourage someone else to memorize subnetting charts and bitswapping charts instead of taking an hour and learning how binary actually works... geez) Mike W. - Original Message - From: Andy Hoang To: Michael L. Williams ; Sent: Monday, July 08, 2002 10:51 PM Subject: RE: Class C summarization question [7:48367] I would say 8 is correct. 4 bits make 8 combinations. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Monday, July 08, 2002 8:15 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48376t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF inter-area summarization [7:44465]
When specifying the summary address, you need to use the network address of the summarization The address you specified is within the summary, its just not the network address. Appling the mask against your address : 0010=32 1100=192 - 00xx=0 Remember 1's we care about, 0's we don't. Now for the network, we set the don't care about bits to 0, (and for the broadcast they are all 1's) This leads to: 00-00 = 0 Your summary is 137.20.1.0 255.255.255.192 This gives a range of address's from 137.20.1.0-137.20.1.63 (network-broadcast) Soo. Area 11 range 137.20.1.0 255.255.255.192 would be the most exact match that you could advertise Thanks Larry -Original Message- From: Michael Witte [mailto:[EMAIL PROTECTED]] Sent: Saturday, May 18, 2002 7:27 PM To: [EMAIL PROTECTED] Subject: OSPF inter-area summarization [7:44465] I am trying to do a lab that needs a inter-area ospf summary address configured I have two loopbacks 137.20.1.17/28 and 137.20.1.33/28. These are then of course on networks 137.20.1.16 and 137.20.1.32. Taking the last octet of the subnets into binary we have: 16= 0001 32= 0010 Acording to Doyle and everything else I have read I should be able to summarize by masking the first two bits. I should be able to use: area 11 range 137.20.1.32 255.255.255.192. I am not able to and the router says I have a invalid address/mask. Furthermore the solution to the lab uses area 11 range 137.20.1.0 255.255.255.0 which creates a summary address to all addresses of 137.20.1.X. What am I missing. This does work and I am able to ping the loopbacks but the math doesn't work for me. I should be able to summarize the 16 and 32 subnets. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44480t=44465 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF inter-area summarization [7:44465]
Larry, I had the idea right to use 255.255.255.192 mask because that is where the bit boundary is. My question is why can't you use the 137.20.1.32/26 to summarize from 32-95. What if you had a subnet zero and didn't want that summarized. Why do I have to use the 137.20.1.0 network for summarization? If we use this example: 172.20.8.0/22 1000 8 172.20.12.0/22 1100 12 ^Bit boundary=248 1000 248 1000 8 subnet 1000 248 mask 1000 8 subnet I think I see now.If you binary AND the subnet and mask and get the subnet you can use that subnet in your summarization. If the binary AND becomes zero, then you must use zero as your network in the summary command. Is this correct? I spent too much time on this and need things like this put to bed for the Lab in November. Thanks. area 11 range 172.20.8.0 255.255.248.0 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44487t=44465 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF inter-area summarization [7:44465]
If I follow what you are saying, then yes, whatever the AND'ing process of the subnet mask and the address space is what your summarization is. Just AND your subnet mask and network statement together. That will give you your summarization range. Case in point, 137.20.1.32 255.255.255.192 Using on the last octet 00 10 = 32 11 00 = 192 00 00 = 0 which is your summarization. Now lets get tricky and summarization 137 and 158 for the 4th octet 10001001 = 137 1000 = 158 1110 = 1 equals common bits, 0's unique.. = 224 Soo 10001001 = 137 1110 = 224 100x = 128 So to summarize these 2 address's as close as possible you would use 137.20.1.128 255.255.255.224 (/27) Notice that I didn't use 137.20.1.137/27 or 137.20.1.158 /27 as if you tried you would get the error you previously mentioned. You would need to use: Area ?? Range 137.20.1.128 255.255.255.224 I hope this makes sense. I'm horrible at explaining things. You should learn sub/super-netting backwards and forwards. Not just for the test, but for real live work experience. On a side note, if you are in the habit of using a subnet calc, I would get out of that habit. I think that they are one of the worst things ever invented. It doesn't aide in the understanding of how IP addressing works, and In fact I think that it allows people to get by without the detailed Knowledge they need. JMHO though :) Thanks Larry -Original Message- From: Michael Witte [mailto:[EMAIL PROTECTED]] Sent: Sunday, May 19, 2002 3:08 PM To: [EMAIL PROTECTED] Subject: Re: OSPF inter-area summarization [7:44465] Larry, I had the idea right to use 255.255.255.192 mask because that is where the bit boundary is. My question is why can't you use the 137.20.1.32/26 to summarize from 32-95. What if you had a subnet zero and didn't want that summarized. Why do I have to use the 137.20.1.0 network for summarization? If we use this example: 172.20.8.0/22 1000 8 172.20.12.0/22 1100 12 ^Bit boundary=248 1000 248 1000 8 subnet 1000 248 mask 1000 8 subnet I think I see now.If you binary AND the subnet and mask and get the subnet you can use that subnet in your summarization. If the binary AND becomes zero, then you must use zero as your network in the summary command. Is this correct? I spent too much time on this and need things like this put to bed for the Lab in November. Thanks. area 11 range 172.20.8.0 255.255.248.0 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44493t=44465 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF inter-area summarization [7:44465]
Great explaination. I just had issues with not being able to use my .32 network address but now I see why.I am taking the road to CCIE very carefully and try to understand exactly why things are the way they are. That is why I love working on the networking end of things; There is a definitive reason for every action. there are also standards(RFC's) that need to be followed. I do a lot of Microsoft stuff at work and you apply a patch that overwrites some .dll and a part of your website doesn't work. Its so frustrating. I worked for 20 years in the electronics field and you could calculate exactly what changing a value would do. this stuff is very simular. Thanks for the help only about 1000 more things to conquer. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44501t=44465 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF inter-area summarization [7:44465]
I am trying to do a lab that needs a inter-area ospf summary address configured I have two loopbacks 137.20.1.17/28 and 137.20.1.33/28. These are then of course on networks 137.20.1.16 and 137.20.1.32. Taking the last octet of the subnets into binary we have: 16= 0001 32= 0010 Acording to Doyle and everything else I have read I should be able to summarize by masking the first two bits. I should be able to use: area 11 range 137.20.1.32 255.255.255.192. I am not able to and the router says I have a invalid address/mask. Furthermore the solution to the lab uses area 11 range 137.20.1.0 255.255.255.0 which creates a summary address to all addresses of 137.20.1.X. What am I missing. This does work and I am able to ping the loopbacks but the math doesn't work for me. I should be able to summarize the 16 and 32 subnets. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44465t=44465 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF inter-area summarization [7:44465]
I am trying to do a lab that needs a inter-area ospf summary address configured I have two loopbacks 137.20.1.17/28 and 137.20.1.33/28. These are then of course on networks 137.20.1.16 and 137.20.1.32. Taking the last octet of the subnets into binary we have: 16= 0001 32= 0010 1 2631 8426 Try .240. You aren't picking up the low-order bits of the summarizable part. Acording to Doyle and everything else I have read I should be able to summarize by masking the first two bits. I should be able to use: area 11 range 137.20.1.32 255.255.255.192. I am not able to and the router says I have a invalid address/mask. Furthermore the solution to the lab uses area 11 range 137.20.1.0 255.255.255.0 which creates a summary address to all addresses of 137.20.1.X. What am I missing. This does work and I am able to ping the loopbacks but the math doesn't work for me. I should be able to summarize the 16 and 32 subnets. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44472t=44465 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF inter-area summarization [7:44465]
Michal Witte Try using area 11 range 137.20.1.0 255.255.255.192 instead. Hope that works. Schwantz Michael Witte wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I am trying to do a lab that needs a inter-area ospf summary address configured I have two loopbacks 137.20.1.17/28 and 137.20.1.33/28. These are then of course on networks 137.20.1.16 and 137.20.1.32. Taking the last octet of the subnets into binary we have: 16= 0001 32= 0010 Acording to Doyle and everything else I have read I should be able to summarize by masking the first two bits. I should be able to use: area 11 range 137.20.1.32 255.255.255.192. I am not able to and the router says I have a invalid address/mask. Furthermore the solution to the lab uses area 11 range 137.20.1.0 255.255.255.0 which creates a summary address to all addresses of 137.20.1.X. What am I missing. This does work and I am able to ping the loopbacks but the math doesn't work for me. I should be able to summarize the 16 and 32 subnets. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44473t=44465 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF summarization for supernet prefix - area0 [7:37739]
Wonder if anyone has ever tried this senario: Router A run both OSPF and IGRP which redistribute into each other. Router R run IGRP with router A. The direct link between A (Ethernet 0) B (Ethernet 0) is /24 (172.16.100.0/24 -IGRP). On router A, there are a prefix with /22 mask which run OSPF Area 0 (Ehthenet 1 - 172.16.200.0/22). In order to force 172.16.200.0/22 into IGRP domain, I do the summary-address 172.16.200.0/24), then router B would be able to see the route (172.16.200.0/24). But on router A, a summary-route also create in the routing table point to null interface (172.16.200.0/24 nexthop NULL 0). In affect, the router will send all traffic to null interface (drop the traffic) for 172.16.200.0 since it has a longer net mask (/24) than the direct link (/22). Any thought or work around for this problem without using static route? Thank you, -Hung __ Do You Yahoo!? Try FREE Yahoo! Mail - the world's greatest free email! http://mail.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=37739t=37739 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF summarization for supernet prefix - area0 [7:37739]
Create a static route on B which points all 172.16.200.0 traffic to A and eliminate the summary route on A. -- RFC 1149 Compliant. HUNG NGUYEN wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Wonder if anyone has ever tried this senario: Router A run both OSPF and IGRP which redistribute into each other. Router R run IGRP with router A. The direct link between A (Ethernet 0) B (Ethernet 0) is /24 (172.16.100.0/24 -IGRP). On router A, there are a prefix with /22 mask which run OSPF Area 0 (Ehthenet 1 - 172.16.200.0/22). In order to force 172.16.200.0/22 into IGRP domain, I do the summary-address 172.16.200.0/24), then router B would be able to see the route (172.16.200.0/24). But on router A, a summary-route also create in the routing table point to null interface (172.16.200.0/24 nexthop NULL 0). In affect, the router will send all traffic to null interface (drop the traffic) for 172.16.200.0 since it has a longer net mask (/24) than the direct link (/22). Any thought or work around for this problem without using static route? Thank you, -Hung __ Do You Yahoo!? Try FREE Yahoo! Mail - the world's greatest free email! http://mail.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=37744t=37739 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Summarization?? What's that? (bug report) [7:37093]
John, You might want to try using the aggregate-address command and see what magic happens. As a side note.. IGP's summarize, whereas BGP being an EGP aggregates. watch the word wrap.. http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr rp_r/bgp_r/1rfbgp1.htm#xtocid1 Nigel - Original Message - From: John Neiberger To: Sent: Sunday, March 03, 2002 12:30 AM Subject: Summarization?? What's that? (bug report) While attempting to summarize some prefixes in BGP I got the following: R3#conf t Enter configuration commands, one per line. End with CNTL/Z. R3(config)#router bgp 2010 R3(config-router)#summa? % Unrecognized command R3(config-router)#summar? % Unrecognized command R3(config-router)#summar ^ % Invalid input detected at '^' marker. R3(config-router)#? Router configuration commands: address-family Enter Address Family command mode aggregate-addressConfigure BGP aggregate entries auto-summary Enable automatic network number summarization bgp BGP specific commands default Set a command to its defaults default-information Control distribution of default information default-metric Set metric of redistributed routes distance Define an administrative distance distribute-list Filter networks in routing updates exit Exit from routing protocol configuration mode help Description of the interactive help system maximum-pathsForward packets over multiple paths neighbor Specify a neighbor router network Specify a network to announce via BGP no Negate a command or set its defaults redistribute Redistribute information from another routing protocol synchronization Perform IGP synchronization table-mapMap external entry attributes into routing table timers Adjust routing timers R3(config-router)# I'm thinking it might be tough to do summarization when the freaking command is missing!! This is a 2500 running 12.1(11) Enterprise Plus. Too weird. I didn't find a bug report for it on CCO but I can't be the only person to run into this. Since I don't feel like doing un upgrade right now, I'll skip that part. John _ Commercial lab list: http://www.groupstudy.com/list/commercial.html Please discuss commercial lab solutions on this list. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=37093t=37093 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Re: Summarization?? What's that? (bug report) [7:37094]
oopsWhat the heck was I thinking?? That's a sure sign I've been studying too long today. I know very well the difference between summary-address and aggregate-address and I still was using the wrong command! Good grief... And even while I was typing my first post I had this nagging feeling that I was overlooking something. :-) Maybe I should have tried using the BGP area range command. heh heh... I think I didn't catch my mistake because another router running 11.2(25a) accepted the command. Now I'm interested to find out what that particular command is doing. This is actually one of my biggest worries when I get to the actual lab. I fear that stuff I've done over and over again will completely slip my mind. Okay, I'm done for the night! Thanks, John On Sun, 3 Mar 2002, Nigel Taylor ([EMAIL PROTECTED]) wrote: John, You might want to try using the aggregate-address command and see what magic happens. As a side note.. IGP's summarize, whereas BGP being an EGP aggregates. watch the word wrap.. http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/ 122cgcr/fipr rp_r/bgp_r/1rfbgp1.htm#xtocid1 Nigel - Original Message - From: John Neiberger To: Sent: Sunday, March 03, 2002 12:30 AM Subject: Summarization?? What's that? (bug report) While attempting to summarize some prefixes in BGP I got the following: R3#conf t Enter configuration commands, one per line. End with CNTL/Z. R3(config)#router bgp 2010 R3(config-router)#summa? % Unrecognized command R3(config-router)#summar? % Unrecognized command R3(config-router)#summar ^ % Invalid input detected at '^' marker. R3(config-router)#? Router configuration commands: address-family Enter Address Family command mode aggregate-addressConfigure BGP aggregate entries auto-summary Enable automatic network number summarization bgp BGP specific commands default Set a command to its defaults default-information Control distribution of default information default-metric Set metric of redistributed routes distance Define an administrative distance distribute-list Filter networks in routing updates exit Exit from routing protocol configuration mode help Description of the interactive help system maximum-pathsForward packets over multiple paths neighbor Specify a neighbor router network Specify a network to announce via BGP no Negate a command or set its defaults redistribute Redistribute information from another routing protocol synchronization Perform IGP synchronization table-mapMap external entry attributes into routing table timers Adjust routing timers R3(config-router)# I'm thinking it might be tough to do summarization when the freaking command is missing!! This is a 2500 running 12.1(11) Enterprise Plus. Too weird. I didn't find a bug report for it on CCO but I can't be the only person to run into this. Since I don't feel like doing un upgrade right now, I'll skip that part. John _ Commercial lab list: http://www.groupstudy.com/list/commercial.html Please discuss commercial lab solutions on this list. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=37094t=37094 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Re: Summarization?? What's that? (bug report) [7:37096]
Just for grins, I tried to find out what summary-address does under BGP in 11.2 but I wasn't able to find a reference for it. The 11.2 Command Reference says that command is only for OSPF and IS-IS, which is what I expected. Still, it's interesting that the router let me make this particular mistake in the BGP config. Oh well, like I said, time to go to bed. I'll sleep off my embarrassment. :-) John On Sun, 3 Mar 2002, John Neiberger ([EMAIL PROTECTED]) wrote: oopsWhat the heck was I thinking?? That's a sure sign I've been studying too long today. I know very well the difference between summary-address and aggregate-address and I still was using the wrong command! Good grief... And even while I was typing my first post I had this nagging feeling that I was overlooking something. :-) Maybe I should have tried using the BGP area range command. heh heh... I think I didn't catch my mistake because another router running 11.2(25a) accepted the command. Now I'm interested to find out what that particular command is doing. This is actually one of my biggest worries when I get to the actual lab. I fear that stuff I've done over and over again will completely slip my mind. Okay, I'm done for the night! Thanks, John On Sun, 3 Mar 2002, Nigel Taylor ([EMAIL PROTECTED]) wrote: John, You might want to try using the aggregate-address command and see what magic happens. As a side note.. IGP's summarize, whereas BGP being an EGP aggregates. watch the word wrap.. http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/ 122cgcr/fipr rp_r/bgp_r/1rfbgp1.htm#xtocid1 Nigel - Original Message - From: John Neiberger To: Sent: Sunday, March 03, 2002 12:30 AM Subject: Summarization?? What's that? (bug report) While attempting to summarize some prefixes in BGP I got the following: R3#conf t Enter configuration commands, one per line. End with CNTL/Z. R3(config)#router bgp 2010 R3(config-router)#summa? % Unrecognized command R3(config-router)#summar? % Unrecognized command R3(config-router)#summar ^ % Invalid input detected at '^' marker. R3(config-router)#? Router configuration commands: address-family Enter Address Family command mode aggregate-addressConfigure BGP aggregate entries auto-summary Enable automatic network number summarization bgp BGP specific commands default Set a command to its defaults default-information Control distribution of default information default-metric Set metric of redistributed routes distance Define an administrative distance distribute-list Filter networks in routing updates exit Exit from routing protocol configuration mode help Description of the interactive help system maximum-pathsForward packets over multiple paths neighbor Specify a neighbor router network Specify a network to announce via BGP no Negate a command or set its defaults redistribute Redistribute information from another routing protocol synchronization Perform IGP synchronization table-mapMap external entry attributes into routing table timers Adjust routing timers R3(config-router)# I'm thinking it might be tough to do summarization when the freaking command is missing!! This is a 2500 running 12.1(11) Enterprise Plus. Too weird. I didn't find a bug report for it on CCO but I can't be the only person to run into this. Since I don't feel like doing un upgrade right now, I'll skip that part. John _ Commercial lab list: http://www.groupstudy.com/list/commercial.html Please discuss commercial lab solutions on this list. _ Commercial lab list: http://www.groupstudy.com/list/commercial.html Please discuss commercial lab solutions on this list. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=37096t=37096 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
NLSP Summarization [7:34326]
Hi All, I am trying to get route sumarization working with NLSP. I have r1 that has networks as follows: Fa0/0 ipx net aaa1 Fa0/1 ipx net aaa2 I have enabled route-aggregation under NLSP but cannot figure out the acl to get only a summary of ' aaa ' advertised to r2 and not aaa1 and aaa2. configs : interface FastEthernet0/0 no ip address no ip directed-broadcast duplex auto speed auto ipx network AAA1 ipx nlsp r1 enable ! interface FastEthernet0/1 no ip address no ip directed-broadcast no keepalive duplex auto speed auto ipx network AAA2 ipx nlsp r1 enable ! ipx router nlsp r1 area-address 0 0 route-aggregation ! ipx access-list summary r1sum deny AAA0 FFF0 permit -1 Any ideas would be appreciated Regards Richard Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=34326t=34326 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Summarization [7:32035]
David, Another thing that I wonder about is the remote end; what do those routers look like? If you have something like this: +-Hub1---Hub3-+ | \ / | RemoteX-+ X +-RemoteY | / \ | +-Hub2---Hub4-+ You'll probably want to restrict what routes the remote routers can advertise. Given the size of your network, it would seem to me that something similar to the following would be more appropriate (disclaimer here, I know nothing of your business requirements nor am I looking at $$ as a limiting factor - which I'm certain it is). I'm making these basic assessments off the fact that your network doesn't seem to follow the standard Cisco Core-Distribution-Access model (yes, I've probably consumed too much of the Cisco Kool-Aid). +-Distr1---Hub1---Hub3---Distr3-+ | |\ /\ /\ /| | RegionA-+ | X X X | +-RegionZ | |/ \/ \/ \| | +-Distr2---Hub2---Hub4---Distr4-+ Within each region you'd have a contiguous block of addresses (both WAN and LAN segments) you then summarize from the distribution-layer routers to the hubs. The hub forward these summary routes to the other hub routers and so on until they reach the remote routers in the other regions. Again, I don't know the requirements of your network but if I were starting with a clean sheet of paper and we wanted to use RFC1918 addresses, I'd probably consider using the 172.x.x.x space. Each region could be a separate /16. If we define the core as the including all of the hub routers as well as the networks connecting them to the various distribution routers and make that the network 172.16.0.0/16 (obviously, there are multiple subnets needed, but they'd all be summarizable in this major net). Then assign a /16 to each region - so RegionA would be 172.17.0.0/16, RegionB would be 172.18.0.0/16, etc. Assuming that you have a data center or two, the server farms in these locations would also connect to the hub routers (ideally behind their own distribution-layer routers which summarize the address space for the server farms into the core). Generally speaking, a design like this will scale into the thousands of sites - obviously YMMV depending on your requirements. The key rule to follow here is that the core of the network is optimized to route packets. This is not the place to enforce network policy (ACLs, QOS, manual summarization, etc.). We all love the network 10.0.0.0/8; it gives us great freedom and allows networks to be built without concern for addressing efficiency. There are some downsides to this though and you've found one. You've been dealt a slightly worse hand though because you sandwich 172.x.x.x networks between 10.x.x.x. I'm going to go out on a limb (kidding) and suggest that your EIGRP configurations have no auto-summary configured, right? In the configuration above, you could allow EIGRP to auto-summarize - you'd actually prefer it because it would mean that you didn't need to manually summarize at all. There are some things you can do to probably make your existing hardware investment work with the current number of sites but it will require that you re-address your network to follow something similar to the design I outlined above just without the separate distribution routers. If you're growing like mad you'll want to ensure that you can get funding for the distribution layer because at some point (if not already) you'll have too many neighbors on each core router which will spark a whole new set of problems. Quickly, on the remote routers, I don't care how big or small the network is, in a (highly) redundant network I try to make sure that each router only advertises networks it's responsible for (e.g. directly connected or down-stream subnets). With EIGRP one of the easiest ways to do this is with the distribute-list command. I try to select a standard ACL number (for example # 5) across the enterprise and then on each router permit only the networks we want - in this case, the remote routers would advertise their directly-connected Ethernet network(s) and maybe a loopback. This will keep EIGRP from thinking that the remote router is a possible transit path to all other networks (especially a problem if you use sub-interfaces on the remote side). Well, I could go on and on but I've got to get back to studying. These are just some suggestions that have worked for me in the past, I'd be interested in what others on the list have experienced. Hope this helps, Ben -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Tuesday, January 15, 2002 5:51 AM To: [EMAIL PROTECTED] Subject: RE:Summarization (to Ben Kessler) [7:31975] Ben, I'm afraid that when I answered your post it was already buried under tons of other post. I'm sorry, these are the consequences of living in Europe...:- Anyway, thanks for your detailed answer, I hope to get more
RE: Summarization [7:31766]
Hello Ben, thanks for your detailed answer. I'm afraid I have no idea what happened but I'm think that it wasn't a problem with CPU unless summarization is a very intensive cpu process(I don't know if it is). We have a hub-and-spoke topology. Four 7500 (2 7513 and 2 7507) for backbone (ATM)and over 230 sites (2500 an 2600 mainly), and we have implemented redundancy using dialers and ISDN connections (and yes, we have conected each router to two different hub routers). In one of the 7513 we have over 100 dialers and 90 serial WANs connections, I have tried the summarization again with only two routers and by now, I haven't experimented any problem. As you can guess, our network is growing more and more and I'm worried about routing tables with a lot of entries (we're using network 172.x.x.x for serial interfaces and 10.x.x.x for ethernet interfaces) I tried to summarize on networks 10.x.x.x and 172.x.x.x using the following commands ip summary-address eigrp 1 10.0.0.0 255.0.0.0 ip summary-address eigrp 1 172.0.0.0 255.0.0.0 Today, I have talked with my boss and we've decided to try the summarization again but we're going to use the 0.0.0.0 network instead the other two (I'll try to check my RSP in-depth this time) Anyway, we're not experts in Cisco so I thought that we could reduce routing tables using summary address and make easier the administration and troubleshooting (perhaps it isn't a good idea). Unfortunatly, we work in a helth-care enviroment, and we have to make sure before doing anything in backbone routers. I hope you read this post, I live in Europe and every time I have to reply a post I have hundreds before me. Anyway, I'll keep you and this wonderful group informed. David Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=31888t=31766 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Summarization [7:31766]
Hello folks, I'm working in a EIGRP enviroment, and I have some questions for you: Has anyone tried to do a manual route sumarization per interface with more or less 200 interfaces in a 7500? I've tried but I'm having a few problems, the summary routes aren't advertised sufficiently fast to the routers in branch offices. The summary routes are sometimes marked as possibly down in the routers of branch offices, sometimes are up and sometimes are down. Do you know any relationship between memory or cpu (or whatever) of the 7500 and number of interfaces in which you can perform manual summarization? David Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=31766t=31766 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Summarization [7:31766]
I've done it with about 100 interfaces on 7513's and didn't see this problem. It may be a limitation of the code on the box, memory (as you indicated), or something else. Have you been able to rule-out as many something elses as possible? What does the network topology look like? Do you have redundancy in place - e.g. spoke routers connected to two different hub routers? Are you getting a lot of SIAs? Routes flapping, etc.? How's the CPU on your RSP's looking? Free memory? Buffer misses? There's a common view that EIGRP works fine and can scale infinitely big without going through all of the steps that you'd have to go through for a large-scale OSPF installation. Obviously, this thought is very wrong. I'm guessing that you need to do manual summarization on 200 interfaces per box is because you don't have clearly-defined summarization points in the network - that's the situation I was in when I had to do it on ~100 interfaces. For good or ill, EIGRP will work with a bad network design (I'm speaking from an ideal perspective - please don't be offended, we all have to things at one time or another that are considered bad) up until a point. Beyond that point, it gets really ugly - quickly. In the network I was working on we had 140 sites connected without problems. We started adding more offices and by the time we hit 170 the network was totally unstable. After several weeks of P1/CAP cases we met with the guys who write the code and found out what we were doing wrong - they have since published several CiscoPress books on EIGRP; none existed four years ago :) You can band-aid a broken network by using a lot of the EIGRP features (manual summarization, distribute-lists, etc.). In my case that's exactly what we did, unfortunately, I was not given the opportunity to correct the mistakes that required the band-aids. I have since moved on to new challenges but that network is still in the same state - four years later. Anyhow, if you can offer more specifics, I'm sure those of us on the list would be happy to comment and offer suggestions. I think that if we can solve the reason you need to manually summarize on 200 interfaces you'll be better off down the road. Ben -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Sunday, January 13, 2002 5:02 AM To: [EMAIL PROTECTED] Subject: Summarization [7:31766] Hello folks, I'm working in a EIGRP enviroment, and I have some questions for you: Has anyone tried to do a manual route sumarization per interface with more or less 200 interfaces in a 7500? I've tried but I'm having a few problems, the summary routes aren't advertised sufficiently fast to the routers in branch offices. The summary routes are sometimes marked as possibly down in the routers of branch offices, sometimes are up and sometimes are down. Do you know any relationship between memory or cpu (or whatever) of the 7500 and number of interfaces in which you can perform manual summarization? David Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=31787t=31766 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Summarization [7:27639]
Matt, Excellent explanation of something often very hard to explain! It is designed to prevent a routing loop which could occur if you inject a supernet to which all included routes arent accounted for I beleive. For example r1 ---r2---r3 R1 has ip addresses 10.1.1.0 - 10.1.9.0 and neighbors with r2 in area 2 R2 enters an area 2 range 10.1.0.0 255.255.240.0 (summarizing 10.1.1.0 - 10.1.15.0) and neighbors with r3 in area 0 R3 issues default information originate so that r2 has a 0/0 route pointing to r3 So...now R3 pings an address at 10.1.10.0 which doesnt really exist. Since it falls within the summary r3 sends the packet to R2. R2 doesnt have a route for the network 10.1.10.0 so it uses the 0/0 route back to R3...and...boom..routing loop. Now you can see what the null route would do. By creating this than it would bit bucket all routes not expicity in the routing table thus preventing the loops. Thats my understanding at any rate. Experts please advise if I am mistaken Luck to All Matt Smith - Original Message - From: Jaspreet Bhatia To: Sent: Wednesday, November 28, 2001 7:51 PM Subject: OSPF Summarization While doing OSPF summarization on an ABR with the area range command , what is the function of including a static route pointing to the NULL interface ? Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=27639t=27639 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Question : Summarization - Routing [7:25923]
Hi, When configuring summary address on eigrp or ospf, a static address for the summary address pointing to the null interface would be added (or I am talked to add the static address in ospf). I don't understand the reason of the static address. Any way to test the situation that shows the reason why I should add it? Any help would be appreciated. BS kang. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=25923t=25923 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Question : Summarization - Routing [7:25923]
The reason for this null interface route is to prevent routing loops. For example, let's say there are two ASes: AS1 and AS2 AS1 - 10.0.0.0/24; 10.0.1.0/24; 10.0.0.0/23 summary route advertising to AS2 default route pointing to AS2 AS2 - 20.0.0.0/24; 20.0.1.0/24; 20.0.0.0/23 summary route advertising to AS1 default route pointing to AS1 If you try and ping from AS2 to 10.0.1.1, it won't be a problem under normal circumstances. However, if 10.0.1.0 disappears for whatever reason within AS1, the following will happen: - Packet from AS2 goes into AS1 - AS1 doesn't know anything about network 10.0.1.0 but AS1 has a default route to AS2 - Packet gets forwarded back to AS2 - AS2 looks up its routing table and forwards it back to AS1 ... and on and on. With a null interface route in place, it will prevent the loop from happening. If we take the scenario above, here's what will happen: - Packet from AS2 goes into AS1 - AS1 doesn't know anything about network 10.0.1.0 but it can match the less specific null interface route (e.g. 10.0.0.0/8 -- null0) - Packet goes into a black hole and error message generated back to originating machine. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=25962t=25923 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Question : Summarization - Routing [7:25923]
Thank you very much. Very clear. -Original Message- From: Blanco Lam [mailto:[EMAIL PROTECTED]] Sent: Tuesday, November 13, 2001 3:13 AM To: [EMAIL PROTECTED] Subject: RE: Question : Summarization - Routing [7:25923] The reason for this null interface route is to prevent routing loops. For example, let's say there are two ASes: AS1 and AS2 AS1 - 10.0.0.0/24; 10.0.1.0/24; 10.0.0.0/23 summary route advertising to AS2 default route pointing to AS2 AS2 - 20.0.0.0/24; 20.0.1.0/24; 20.0.0.0/23 summary route advertising to AS1 default route pointing to AS1 If you try and ping from AS2 to 10.0.1.1, it won't be a problem under normal circumstances. However, if 10.0.1.0 disappears for whatever reason within AS1, the following will happen: - Packet from AS2 goes into AS1 - AS1 doesn't know anything about network 10.0.1.0 but AS1 has a default route to AS2 - Packet gets forwarded back to AS2 - AS2 looks up its routing table and forwards it back to AS1 ... and on and on. With a null interface route in place, it will prevent the loop from happening. If we take the scenario above, here's what will happen: - Packet from AS2 goes into AS1 - AS1 doesn't know anything about network 10.0.1.0 but it can match the less specific null interface route (e.g. 10.0.0.0/8 -- null0) - Packet goes into a black hole and error message generated back to originating machine. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=26031t=25923 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF Route Summarization Trick Question [7:23771]
Okay, this doesn't quite qualify as a trick question but I'm having trouble finding the answer. I hope it's not too obvious or I'll be embarrassed. :-) While working on one of the Fatkid's labs I see the following in the Hints sections: 3. There are two built in OSPF methods to summarize OSPF routes. One way summaries between areas. The other summarizes between Autonomous Systems. Do you know a third way to summarize routes, which works for any router, running any routing protocol? How about a fourth? I was quite aware of the first two but I have no idea what the last two could be. I'm especially interested in the the method that works for any router running any routing protocol. I really have a feeling I'm going to kick myself when someone tells me what that is. Do any of you know what they're referring to? Thanks, John Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=23771t=23771 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Route Summarization Trick Question [7:23771]
Here's my guess. I've included the first two for clarity. 1. Inter-area route summarization with commands of the form area 1 range 10.1.2.0 255.255.224.0 2. External route summarization with commands of the form summary-address 10.1.2.0 225.255.224.0 3. Static route of the form ip route 10.1.2.0 255.255.224.0 s0 4. ?? John Neiberger wrote: Okay, this doesn't quite qualify as a trick question but I'm having trouble finding the answer. I hope it's not too obvious or I'll be embarrassed. :-) While working on one of the Fatkid's labs I see the following in the Hints sections: 3. There are two built in OSPF methods to summarize OSPF routes. One way summaries between areas. The other summarizes between Autonomous Systems. Do you know a third way to summarize routes, which works for any router, running any routing protocol? How about a fourth? I was quite aware of the first two but I have no idea what the last two could be. I'm especially interested in the the method that works for any router running any routing protocol. I really have a feeling I'm going to kick myself when someone tells me what that is. Do any of you know what they're referring to? Thanks, John Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=23775t=23771 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Route Summarization Trick Question [7:23771]
I thought of that solution (#3) but I wasn't sure if that was what he was referring to. Usually, in the context of CCIE lab studies, the labs state that you can't use static routes. However, this wasn't part of the lab, it was just in the Hints section of a lab so that restriction might not have applied. I'm sure you're right. Also, a static route wouldn't suppress the more-specific subnets. Is there a way similar to this to summarize routes AND to suppress the more-specific subnets? Hmm food for thought. I'm still at a loss about the fourth method. I wonder if it involves some sort of incantation. Thanks, John Jonathan Hays 10/22/01 9:01:49 AM Here's my guess. I've included the first two for clarity. 1. Inter-area route summarization with commands of the form area 1 range 10.1.2.0 255.255.224.0 2. External route summarization with commands of the form summary-address 10.1.2.0 225.255.224.0 3. Static route of the form ip route 10.1.2.0 255.255.224.0 s0 4. ?? John Neiberger wrote: Okay, this doesn't quite qualify as a trick question but I'm having trouble finding the answer. I hope it's not too obvious or I'll be embarrassed. :-) While working on one of the Fatkid's labs I see the following in the Hints sections: 3. There are two built in OSPF methods to summarize OSPF routes. One way summaries between areas. The other summarizes between Autonomous Systems. Do you know a third way to summarize routes, which works for any router, running any routing protocol? How about a fourth? I was quite aware of the first two but I have no idea what the last two could be. I'm especially interested in the the method that works for any router running any routing protocol. I really have a feeling I'm going to kick myself when someone tells me what that is. Do any of you know what they're referring to? Thanks, John [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=23776t=23771 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF Route Summarization Trick Question [7:23771]
Yep, distribute-lists could work in conjuction with Jonathan's suggestion of redistributing a static route. I wanted to know how to suppress the more-specific subnets and a distribute list would work. It would be pretty unwieldy for more than a few routes but it definitely would work. Are you thinking of a method that uses only distribute lists without the static route? If so, let me know what you're thinking, I'd love to try it out. I know that would work in cases where, like in EIGRP, a classful supernet often resides in the routing table along with the more-specific subnets. A distribute list could be used to filter only the subnets. Thanks, John Jim Dixon 10/22/01 9:10:00 AM Hi John, What about Distribute lists? (in/out??) -Original Message- From: John Neiberger [mailto:[EMAIL PROTECTED]] Sent: Monday, October 22, 2001 09:33 To: [EMAIL PROTECTED] Subject: OSPF Route Summarization Trick Question [7:23771] Okay, this doesn't quite qualify as a trick question but I'm having trouble finding the answer. I hope it's not too obvious or I'll be embarrassed. :-) While working on one of the Fatkid's labs I see the following in the Hints sections: 3. There are two built in OSPF methods to summarize OSPF routes. One way summaries between areas. The other summarizes between Autonomous Systems. Do you know a third way to summarize routes, which works for any router, running any routing protocol? How about a fourth? I was quite aware of the first two but I have no idea what the last two could be. I'm especially interested in the the method that works for any router running any routing protocol. I really have a feeling I'm going to kick myself when someone tells me what that is. Do any of you know what they're referring to? Thanks, John Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=23778t=23771 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF Route Summarization Trick Question [7:23771]
I was thinking of using an ACL with Distribute List. Your paragraph states that the solutions must work with any router and any protocol. Static Routes would be my first choice here provided the lab directions didn't prevent this choice. What did the directions for the LAB state? Were there any that stated that you must not use a certain method for any questions in this particular lab? Why did the question begin asking about OSPF then ask if there were other ways to accomplish the same goal by using a non-protocol dependent, non-router platform dependent method? -Original Message- From: John Neiberger [mailto:[EMAIL PROTECTED]] Sent: Monday, October 22, 2001 10:14 To: [EMAIL PROTECTED] Subject: RE: OSPF Route Summarization Trick Question [7:23771] Yep, distribute-lists could work in conjuction with Jonathan's suggestion of redistributing a static route. I wanted to know how to suppress the more-specific subnets and a distribute list would work. It would be pretty unwieldy for more than a few routes but it definitely would work. Are you thinking of a method that uses only distribute lists without the static route? If so, let me know what you're thinking, I'd love to try it out. I know that would work in cases where, like in EIGRP, a classful supernet often resides in the routing table along with the more-specific subnets. A distribute list could be used to filter only the subnets. Thanks, John Jim Dixon 10/22/01 9:10:00 AM Hi John, What about Distribute lists? (in/out??) -Original Message- From: John Neiberger [mailto:[EMAIL PROTECTED]] Sent: Monday, October 22, 2001 09:33 To: [EMAIL PROTECTED] Subject: OSPF Route Summarization Trick Question [7:23771] Okay, this doesn't quite qualify as a trick question but I'm having trouble finding the answer. I hope it's not too obvious or I'll be embarrassed. :-) While working on one of the Fatkid's labs I see the following in the Hints sections: 3. There are two built in OSPF methods to summarize OSPF routes. One way summaries between areas. The other summarizes between Autonomous Systems. Do you know a third way to summarize routes, which works for any router, running any routing protocol? How about a fourth? I was quite aware of the first two but I have no idea what the last two could be. I'm especially interested in the the method that works for any router running any routing protocol. I really have a feeling I'm going to kick myself when someone tells me what that is. Do any of you know what they're referring to? Thanks, John Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=23785t=23771 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF Route Summarization Trick Question [7:23771]
In this particular lab static routes were forbidden. It was an OSPF lab and one of the instructions was to configure summarization between areas. The Hints section was there to prompt us on different ways this might be accomplished. Since it's a training lab they're trying to make us think of different ways to do the same thing in case some of them are not allowed in the actual lab exam. John Jim Dixon 10/22/01 10:17:23 AM I was thinking of using an ACL with Distribute List. Your paragraph states that the solutions must work with any router and any protocol. Static Routes would be my first choice here provided the lab directions didn't prevent this choice. What did the directions for the LAB state? Were there any that stated that you must not use a certain method for any questions in this particular lab? Why did the question begin asking about OSPF then ask if there were other ways to accomplish the same goal by using a non-protocol dependent, non-router platform dependent method? -Original Message- From: John Neiberger [mailto:[EMAIL PROTECTED]] Sent: Monday, October 22, 2001 10:14 To: [EMAIL PROTECTED] Subject: RE: OSPF Route Summarization Trick Question [7:23771] Yep, distribute-lists could work in conjuction with Jonathan's suggestion of redistributing a static route. I wanted to know how to suppress the more-specific subnets and a distribute list would work. It would be pretty unwieldy for more than a few routes but it definitely would work. Are you thinking of a method that uses only distribute lists without the static route? If so, let me know what you're thinking, I'd love to try it out. I know that would work in cases where, like in EIGRP, a classful supernet often resides in the routing table along with the more-specific subnets. A distribute list could be used to filter only the subnets. Thanks, John Jim Dixon 10/22/01 9:10:00 AM Hi John, What about Distribute lists? (in/out??) -Original Message- From: John Neiberger [mailto:[EMAIL PROTECTED]] Sent: Monday, October 22, 2001 09:33 To: [EMAIL PROTECTED] Subject: OSPF Route Summarization Trick Question [7:23771] Okay, this doesn't quite qualify as a trick question but I'm having trouble finding the answer. I hope it's not too obvious or I'll be embarrassed. :-) While working on one of the Fatkid's labs I see the following in the Hints sections: 3. There are two built in OSPF methods to summarize OSPF routes. One way summaries between areas. The other summarizes between Autonomous Systems. Do you know a third way to summarize routes, which works for any router, running any routing protocol? How about a fourth? I was quite aware of the first two but I have no idea what the last two could be. I'm especially interested in the the method that works for any router running any routing protocol. I really have a feeling I'm going to kick myself when someone tells me what that is. Do any of you know what they're referring to? Thanks, John Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=23790t=23771 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: route summarization question [7:19970]
Cisco wrong? Perish the thought!!! ;- seeing as 134 is 1110, and is in no way relevant here, I would suggest that the lazy no good subcontractor that Cisco hired to write / proof / tech review / whatever is wrong. welcome to the world of study materials. best wishes Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of The New Guy Sent: Friday, September 14, 2001 9:19 AM To: [EMAIL PROTECTED] Subject: route summarisation question [7:19970] A buddy and I are currently preparing for the BSCN exam. One of the review questions involving route summarization is as follows: 172.21.136.0/24 and 172.21.143.0/24 can be summarized as: ?? We both came to the same conclusion: ^ 172.21.136.0 - 10101100.00010101.10001000. 172.21.143.0 - 10101100.00010101.1000. ^ Both addresses have the first 20 bits in common so the summarized address would be: 172.21.136.0/21 However, Cisco says the answer is 172.21.134.0/21 Can someone please confirm we summarized this route right. I think the test from Cisco is wrong, typo or something Dyland Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=19980t=19970 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: route summarization question [7:19970]
dammit, Leigh Anne, now EVERYONE will know who to blame for any technical errors they catch! ;- -Original Message- From: Leigh Anne Chisholm [mailto:[EMAIL PROTECTED]] Sent: Friday, September 14, 2001 10:53 AM To: Chuck Larrieu; [EMAIL PROTECTED]; The New Guy Subject: RE: route summarization question [7:19970] To determine whether the question you have is right or wrong, take 172.21.134.0 and apply the mask 255.255.248.0. What range of addresses does this mask give you? 172.21.128.0 through 172.21.135.255. Now does that represent the range of IP addresses you've been asked to summarize? I think not. Let's try your answer. Take 172.21.136.0 and apply the mask 255.255.248.0. What range of addresses does that mask give you? 172.21.136.0 through 172.21.143.255. Does it fit the criteria for the question? Does it represent 172.21.136.0 and 172.21.143.0? Chuck's comments about the lazy no good subcontractor is kind of funny, because he's been an absolutely awesome technical editor for Sybex's new CCNP exam series... (-: -- Leigh Anne -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Chuck Larrieu Sent: Friday, September 14, 2001 11:24 AM To: [EMAIL PROTECTED] Subject: RE: route summarization question [7:19970] Cisco wrong? Perish the thought!!! ;- seeing as 134 is 1110, and is in no way relevant here, I would suggest that the lazy no good subcontractor that Cisco hired to write / proof / tech review / whatever is wrong. welcome to the world of study materials. best wishes Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of The New Guy Sent: Friday, September 14, 2001 9:19 AM To: [EMAIL PROTECTED] Subject: route summarisation question [7:19970] A buddy and I are currently preparing for the BSCN exam. One of the review questions involving route summarization is as follows: 172.21.136.0/24 and 172.21.143.0/24 can be summarized as: ?? We both came to the same conclusion: ^ 172.21.136.0 - 10101100.00010101.10001000. 172.21.143.0 - 10101100.00010101.1000. ^ Both addresses have the first 20 bits in common so the summarized address would be: 172.21.136.0/21 However, Cisco says the answer is 172.21.134.0/21 Can someone please confirm we summarized this route right. I think the test from Cisco is wrong, typo or something Dyland Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=19984t=19970 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: route summarization question [7:19970]
To determine whether the question you have is right or wrong, take 172.21.134.0 and apply the mask 255.255.248.0. What range of addresses does this mask give you? 172.21.128.0 through 172.21.135.255. Now does that represent the range of IP addresses you've been asked to summarize? I think not. Let's try your answer. Take 172.21.136.0 and apply the mask 255.255.248.0. What range of addresses does that mask give you? 172.21.136.0 through 172.21.143.255. Does it fit the criteria for the question? Does it represent 172.21.136.0 and 172.21.143.0? Chuck's comments about the lazy no good subcontractor is kind of funny, because he's been an absolutely awesome technical editor for Sybex's new CCNP exam series... (-: -- Leigh Anne -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Chuck Larrieu Sent: Friday, September 14, 2001 11:24 AM To: [EMAIL PROTECTED] Subject: RE: route summarization question [7:19970] Cisco wrong? Perish the thought!!! ;- seeing as 134 is 1110, and is in no way relevant here, I would suggest that the lazy no good subcontractor that Cisco hired to write / proof / tech review / whatever is wrong. welcome to the world of study materials. best wishes Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of The New Guy Sent: Friday, September 14, 2001 9:19 AM To: [EMAIL PROTECTED] Subject: route summarisation question [7:19970] A buddy and I are currently preparing for the BSCN exam. One of the review questions involving route summarization is as follows: 172.21.136.0/24 and 172.21.143.0/24 can be summarized as: ?? We both came to the same conclusion: ^ 172.21.136.0 - 10101100.00010101.10001000. 172.21.143.0 - 10101100.00010101.1000. ^ Both addresses have the first 20 bits in common so the summarized address would be: 172.21.136.0/21 However, Cisco says the answer is 172.21.134.0/21 Can someone please confirm we summarized this route right. I think the test from Cisco is wrong, typo or something Dyland Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=19982t=19970 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: route summarization question [7:19970]
cat's outta da bag now. but i'm sure your name will be there (Technical Editor, Chuck Larrieu, CCIE 82**) on the front of every text. ;-) -e- - Original Message - From: Chuck Larrieu To: Sent: Friday, September 14, 2001 11:11 AM Subject: RE: route summarization question [7:19970] dammit, Leigh Anne, now EVERYONE will know who to blame for any technical errors they catch! ;- -Original Message- From: Leigh Anne Chisholm [mailto:[EMAIL PROTECTED]] Sent: Friday, September 14, 2001 10:53 AM To: Chuck Larrieu; [EMAIL PROTECTED]; The New Guy Subject: RE: route summarization question [7:19970] To determine whether the question you have is right or wrong, take 172.21.134.0 and apply the mask 255.255.248.0. What range of addresses does this mask give you? 172.21.128.0 through 172.21.135.255. Now does that represent the range of IP addresses you've been asked to summarize? I think not. Let's try your answer. Take 172.21.136.0 and apply the mask 255.255.248.0. What range of addresses does that mask give you? 172.21.136.0 through 172.21.143.255. Does it fit the criteria for the question? Does it represent 172.21.136.0 and 172.21.143.0? Chuck's comments about the lazy no good subcontractor is kind of funny, because he's been an absolutely awesome technical editor for Sybex's new CCNP exam series... (-: -- Leigh Anne -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Chuck Larrieu Sent: Friday, September 14, 2001 11:24 AM To: [EMAIL PROTECTED] Subject: RE: route summarization question [7:19970] Cisco wrong? Perish the thought!!! ;- seeing as 134 is 1110, and is in no way relevant here, I would suggest that the lazy no good subcontractor that Cisco hired to write / proof / tech review / whatever is wrong. welcome to the world of study materials. best wishes Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of The New Guy Sent: Friday, September 14, 2001 9:19 AM To: [EMAIL PROTECTED] Subject: route summarisation question [7:19970] A buddy and I are currently preparing for the BSCN exam. One of the review questions involving route summarization is as follows: 172.21.136.0/24 and 172.21.143.0/24 can be summarized as: ?? We both came to the same conclusion: ^ 172.21.136.0 - 10101100.00010101.10001000. 172.21.143.0 - 10101100.00010101.1000. ^ Both addresses have the first 20 bits in common so the summarized address would be: 172.21.136.0/21 However, Cisco says the answer is 172.21.134.0/21 Can someone please confirm we summarized this route right. I think the test from Cisco is wrong, typo or something Dyland _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=20014t=19970 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Just how important is route summarization in t [7:14783]
I do think I was misunderstood here. 1. Classless addressing is the worldwide standard no matter what Cisco says, and should be the default approach to address assignment. 2. Summarization/aggregation/supernetting should be used WHEN POSSIBLE, but controlled exceptions can make sense. 3. Having the full routing table available makes debugging HARDER, not easier. The primary tools should be DOCUMENTATION, ping, and traceroute. 4. Redistribution isn't always a temporary fix. While it should be regarded as such when converting from a less capable (e.g., IGRP) to a more capable (e.g., OSPF, EIGRP) routing protocol, there are perfectly valid reasons to do redistribution of static routes, to selectively redistribute into RIP in the specific case where it is being used to help hosts find specific gateways, and, WHEN YOU KNOW EXACTLY WHAT YOU ARE DOING, in and out of BGP. At 03:15 PM 8/3/2001 -0400, you wrote: [EMAIL PROTECTED] wrote: I agree with you, Howard. All the best practices I have ever learned have stated that route summarization should be avoided, and, if not possible, at least minimized. I think unless you have a large network with multiple AS's, route summarization should only be considered a temporary fix until a common protocol is chosen and can be implemented. I consider it to be along the lines of using Virtual Links. My .02c, Rob H. CCNP, CCDP, MCSE Now that I'm re-reading this, it seems your must be talking about redistribution, not summarization. The comment ... a temporary fix until a common protocol is chosen and can be implemented. could only be referring to using redistribution, and it being a temporary fix. And although I've seen many places that used it constantly, all of the design guides I've read say that redistribution should be used temporarily while coverting from one routing protocol to another. Are you sure that you're talking about summarization and not redistribution? Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14944t=14783 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Just how important is route summarization in typical [7:14947]
At 10:01 PM 8/3/2001 -0400, Chuck Larrieu wrote: as someone who once was in the position of managing help desk and system admins, I have to butt in and say that the toughest problem I had in that respect was getting people to think for themselves. I had employees whose answer to everything was to reformat the hard drive, or reboot the modem the net CSU's ) or worse yet come and ask me how to solve the problem ( why do I need you if I'm doing all the work anyway? ) it could well be that the subordinates in question are lacking clue of any kind. Chuck I will claim temporary timezone insanity here in England, but you remind me of one of the rejected plot lines in the movie Pretty Woman. Julia Roberts was to have been taken to the Gardening and Fine Arts Society to shine, but, alas, became a social and intellectual failure there. Proving the adage, you can lead a horticulture but you can't make her think. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of GB Sent: Friday, August 03, 2001 5:12 PM To: [EMAIL PROTECTED] Subject: Re: Just how important is route summarization in typical [7:14854] Just ignore him DJ, what he's trying to do is just retain his job security as head idiot. By telling his management that he is surrounded by a bunch of very junior NT admins that can't do anything without him, he tries to quanlify his value and necessity to the organization. What make an excellent manager is not one that can do everything, but teach difficult concepts effectively and delegate those responsibilities appropriately. CIO material this guy is definately not. As for working under this guy, how many of us would like to be greeted by Allright, punk-ass bitch what the hell do you not understand now?!?! as the beginning of his training sessions. I don't blame his very junior NT admins from trying to stay away as far as possible from this guy... - Original Message - From: Donald B Johnson jr To: Sent: Friday, August 03, 2001 2:38 PM Subject: Fw: Just how important is route summarization in typical [7:14842] I dont think this guy is stable. And it is still a moronic discussion. Who cares that he can't summarize because he is surronded by idiots. I mean am I missing something here. - Original Message - From: nrf To: Donald B Johnson jr Sent: Friday, August 03, 2001 2:05 PM Subject: Re: Just how important is route summarization in typical [7:14814] Allright, punk-ass bitch. You got a problem with me? Did I ruin your day? Why don't we meet somewhere and we'll settle it like men? Anytime, anyplace, bitch. - Original Message - From: Donald B Johnson jr To: nrf ; Sent: Friday, August 03, 2001 3:54 PM Subject: Re: Just how important is route summarization in typical [7:14814] Its nothing but morons for a fifty mile radius from you, and you can't use summarization because only you, the delhi-lama and elvs could ever understand it. What does this have to do with the original question. Why don't you just type up a spread sheet and paste it on the side of the router, they will never know if the routes are summarized. This is one of the most moronic discussions on this lists in a long time. Why are they just having a problem with summarization, if they are so dumb. Oh and technically speaking supernets and summarization are two different things but I was hoping that delhi-lama elvis would knock ya off your high horse. I'll throw you a bone there biff, Not All Summarized routes are Supernets. Call me at 3am when you figure it out. - Original Message - From: nrf To: Sent: Friday, August 03, 2001 11:26 AM Subject: Re: Just how important is route summarization in typical [7:14814] My biggest problem with summarization so far: Ring-Ring-Ring - my cellphone goes off at 3AM, I'm rudely awakened and blearily reach for it: Hello? - I say weakly Hey boss, I'm on the office router, and I can't see all the routes!!! Well, that's probably because I summarized it, and you can only see the supernets Uhh, boss, what's summarization? What's a supernet? That's my biggest problem with summarization right there, it requires a higher level of understanding than my guys have. I got a bunch of (very) junior guys who know how to get into the router, they know how to do show ip route , and they know how to ping, and that's pretty much about it as far as networks go.They don't know the intricacies of subnetting, supernetting, blah blah blah, I don't have time to teach them, and quite frankly I don't think they want to know anyway (they're just NT admins, and that's what they want to spend their time doing). All they want, and all
Re: Just how important is route summarization in typical [7:14948]
At 11:51 PM 8/3/2001 -0400, nrf wrote: OK all - well, I'd like to wrap up my original post .For those who don't know, I was the person who originally started this post on summarization, and it has apparently taken a life of its own (I cringed when I first started this thread because I had a feeling that it might invite a few hecklers, and sure enough, there they were). I apologize to all you who had to witness my response to them, but hey, what can I say, I hate flamers. I don't want to disrespect anybody, but on the other hand I really don't want people disrespecting me. So anyway, enough about that. I would like to summarize some of the pros and cons of summarization. Thank you for everybody who replied with something constructive. Here is what I got. Pros: 1) Faster route-lookup, particularly with very large route tables (on the order of thousands of routes) Generally not true, except in the specific cases of autonomous or silicon switching. Modern route lookup time is largely independent of the number of routes. When I say route lookup, I'm talking about forwarding.Routing table update speed is significantly dependent on the number of routes (as well as other factors). 2) Masking of route instabilities 3) Increased scalability of certain routing protocols (for example, the OSPF database size increases to the square of the number of networks without summarization, but increases only linearly with proper summarization) Cons 1) More difficult to understand the route table - need to understand the true nature of subnetting (this may not be a big deal to most of us, but trust me it is a very big deal to some people). 2) Suboptimal routing (granted, this may not be as big a concern as I had first though). And then of course, the applicability of summarization is very much topology driven (as discussed by Chuck Larrieu and Michael Williams below). One should, I would think, not just throw summarized networks throughout your enterprise willy-nilly, but do so only with an understanding of your network. Anything have anything (constructive) to add or change? One compromise -- design your addressing plan hierarchically, so if you do subsequently need to summarize, you don't need to renumber. Thanks Chuck Larrieu wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Mike, yours is about the best message in this thread to use as a start point for some random thoughts. seems to me that there are architectures and network sizes that do and do not lend themselves to summarization. for example, in the typical small network hub and spoke setup, it's questionable whether or not routing protocols are even required. static routes or Cisco On Demand Routing are probably more than sufficient. yes the books all say that static routing doesn't scale. but consider the company that starts with a central site and 10 branch offices, and adds a branch every six months. shared services are all at the hub. the branches don't care about eachother's existence. most of us throw EIGRP onto the routers and have done with it. but in truth, it is unnecessary. there isn't a lot of work here, and this is probably good for as long as the model applies. in the case where a new domain is added into an existing network, summarization can be quite useful. for example, I am working with a customer who is setting up an RLAN as a telecommute network ( DSL at the user side, ATM at the host side )under the original design, there would have been one net for each wan link, and one net for each home user device, /30s in all cases. rather than advertise hundreds of /30's we planned on summarization, advertising only two routes into the corporate domain. another interesting case I came across at another customer site. EIGRP everywhere in a campus environment. multiple buildings, half of which were connected via fiber and switches, the other half of which were connected by T1's and routers. discontiguous subnets everywhere. we determined that there were two entry points from the routed domains into the corporate network, and we figured we could summarize at the classful boundary at each of these entry points, and advertise those summaries to the appropriate domain. I'll have to look up my notes on the topology in this case. it made sense to summarize at the time. what I am getting at is that topology can be the main driver in determining the usefulness of summarization. since the question was asked, I am assuming that the asker works in an environment where summarization is possible and makes sense ( except for the issue of the clueless subordinates, but that's another story. good post, Mike. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Thursday, August 02, 2001 5:19 PM To: [EMAIL PROTECTED] Subject: Re:
Re: Just how important is route summarization in typical [7:14953]
Howard C. Berkowitz wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... One compromise -- design your addressing plan hierarchically, so if you do subsequently need to summarize, you don't need to renumber. Is there any case when using hierarchical addressing where you *wouldn't* want to summarize. Don't get me wrong, I'm not saying you have to implement summarization everywhere possible, but is there are specific downside to summarizing everywhere you can? Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14953t=14953 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Just how important is route summarization in typical [7:14964]
in the case of a hub and spoke network, where implementing summarization on the spokes (or rather, advertising of summaries out the interfaces of the hub) yields extra configuration work with no real benefit? in a small network, no matter what the topology, where the number of routes is minimal, again leading to a extra configuration work and no real benefit? in these two cases, even the extra work is not all that much. considering the time I used to spend tweaking, revising, and otherwise fooling around with my WAN addressing and encapsulation, it is insignificant in the grand scheme of things. in an operation where you have clueless low level NOC people who just don't get it, and repeatedly bother the network manager with midnight calls reporting they don't see all the routes they think they should be seeing? (which I believe was the genesis of this thread) where would you see a disadvantage? Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Sunday, August 05, 2001 9:26 AM To: [EMAIL PROTECTED] Subject: Re: Just how important is route summarization in typical [7:14953] Howard C. Berkowitz wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... One compromise -- design your addressing plan hierarchically, so if you do subsequently need to summarize, you don't need to renumber. Is there any case when using hierarchical addressing where you *wouldn't* want to summarize. Don't get me wrong, I'm not saying you have to implement summarization everywhere possible, but is there are specific downside to summarizing everywhere you can? Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14964t=14964 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Just how important is route summarization in typical [7:14745]
She has a way of doing that =) Mike W. nrf wrote in message news:[EMAIL PROTECTED]... Thank you Priscilla. You said it better than I ever could. I guess this is why you're a famous author and I'm not. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14745t=14745 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Just how important is route summarization in typical [7:14814]
My biggest problem with summarization so far: Ring-Ring-Ring - my cellphone goes off at 3AM, I'm rudely awakened and blearily reach for it: Hello? - I say weakly Hey boss, I'm on the office router, and I can't see all the routes!!! Well, that's probably because I summarized it, and you can only see the supernets Uhh, boss, what's summarization? What's a supernet? That's my biggest problem with summarization right there, it requires a higher level of understanding than my guys have. I got a bunch of (very) junior guys who know how to get into the router, they know how to do show ip route , and they know how to ping, and that's pretty much about it as far as networks go.They don't know the intricacies of subnetting, supernetting, blah blah blah, I don't have time to teach them, and quite frankly I don't think they want to know anyway (they're just NT admins, and that's what they want to spend their time doing). All they want, and all I want for them, is to be able to go to any router, and look for all the routes in the network, that's all. I suppose the presumption was that only I, or other skilled network guys were taking care of this network, and this is not so. I hope everybody sees in this light why I have an objection of using it in my network. I am not particularly inclined to do anything even a little bit complex because I am not the one who is going to maintain it. Ultimately, it's a manageability thing. Howard C. Berkowitz wrote in message news:[EMAIL PROTECTED]... At 05:07 PM 8/2/2001 -0400, you wrote: Ah, but why stop at 3, why not 30 or 300 or 3000 disasters all at once? Reason being at some point it really is not cost-effective to try to engineer your systems to be even more safe, because the extra safety margin is not worth the massive amount of money you have to spend. So, goes to what I thought was my original question (but apparently it has been twisted around, so let me ask it again) - how large does your network have to grow before it really starts to benefit from summarization? As I'm sure we're all aware, summarization is not all good, there are some bad points to it - the biggest being that it is just simply harder to troubleshoot a summarized network (because I can't see all the routes from all my routers). That puzzles me. I find summarization makes it easier to troubleshoot -- binary search versus linear search, if you will. By the way, I worked in the oil field for 9 years, and it's pretty dangerous. I've known people that died, and using systems that certainly were not engineered to take 3 disasters at once. Bill Pearch wrote in message news:[EMAIL PROTECTED]... Yes! An oil field engineer summed it up this way: When designing something, design it so three disasters have to happen at the same time before someone gets killed. I hate it when networks just happen. TTFN, Bill -Original Message- From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]] Sent: Thursday, August 02, 2001 12:13 PM To: [EMAIL PROTECTED] Subject: Re: Just how important is route summarization in typical [7:14700] In our industry, we assume something is going to wrong and plan for it. We plan how to minimize the affects of a link going down. My $0.0002 Priscilla Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14814t=14814 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Just how important is route summarization in typical [7:14841]
Hello- who the hell is the Delhi lama? It's the Dalai Lama, dumb-ass. It's Elvis, not elvs. Go back to grade school and learn how to spell. Donald B Johnson jr wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Its nothing but morons for a fifty mile radius from you, and you can't use summarization because only you, the delhi-lama and elvs could ever understand it. What does this have to do with the original question. Why don't you just type up a spread sheet and paste it on the side of the router, they will never know if the routes are summarized. This is one of the most moronic discussions on this lists in a long time. Why are they just having a problem with summarization, if they are so dumb. Oh and technically speaking supernets and summarization are two different things but I was hoping that delhi-lama elvis would knock ya off your high horse. I'll throw you a bone there biff, Not All Summarized routes are Supernets. Call me at 3am when you figure it out. - Original Message - From: nrf To: Sent: Friday, August 03, 2001 11:26 AM Subject: Re: Just how important is route summarization in typical [7:14814] My biggest problem with summarization so far: Ring-Ring-Ring - my cellphone goes off at 3AM, I'm rudely awakened and blearily reach for it: Hello? - I say weakly Hey boss, I'm on the office router, and I can't see all the routes!!! Well, that's probably because I summarized it, and you can only see the supernets Uhh, boss, what's summarization? What's a supernet? That's my biggest problem with summarization right there, it requires a higher level of understanding than my guys have. I got a bunch of (very) junior guys who know how to get into the router, they know how to do show ip route , and they know how to ping, and that's pretty much about it as far as networks go.They don't know the intricacies of subnetting, supernetting, blah blah blah, I don't have time to teach them, and quite frankly I don't think they want to know anyway (they're just NT admins, and that's what they want to spend their time doing). All they want, and all I want for them, is to be able to go to any router, and look for all the routes in the network, that's all. I suppose the presumption was that only I, or other skilled network guys were taking care of this network, and this is not so. I hope everybody sees in this light why I have an objection of using it in my network. I am not particularly inclined to do anything even a little bit complex because I am not the one who is going to maintain it. Ultimately, it's a manageability thing. Howard C. Berkowitz wrote in message news:[EMAIL PROTECTED]... At 05:07 PM 8/2/2001 -0400, you wrote: Ah, but why stop at 3, why not 30 or 300 or 3000 disasters all at once? Reason being at some point it really is not cost-effective to try to engineer your systems to be even more safe, because the extra safety margin is not worth the massive amount of money you have to spend. So, goes to what I thought was my original question (but apparently it has been twisted around, so let me ask it again) - how large does your network have to grow before it really starts to benefit from summarization? As I'm sure we're all aware, summarization is not all good, there are some bad points to it - the biggest being that it is just simply harder to troubleshoot a summarized network (because I can't see all the routes from all my routers). That puzzles me. I find summarization makes it easier to troubleshoot -- binary search versus linear search, if you will. By the way, I worked in the oil field for 9 years, and it's pretty dangerous. I've known people that died, and using systems that certainly were not engineered to take 3 disasters at once. Bill Pearch wrote in message news:[EMAIL PROTECTED]... Yes! An oil field engineer summed it up this way: When designing something, design it so three disasters have to happen at the same time before someone gets killed. I hate it when networks just happen. TTFN, Bill -Original Message- From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]] Sent: Thursday, August 02, 2001 12:13 PM To: [EMAIL PROTECTED] Subject: Re: Just how important is route summarization in typical [7:14700] In our industry, we assume something is going to wrong and plan for it. We plan how to minimize the affects of a link going down. My $0.0002 Priscilla Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14841t=14841 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondi
Re: Just how important is route summarization in typical [7:14848]
As far as the summarization vs. supernetting thing - here goes. Summarization is a general idea where several more specific routes are coupled - aggregated if you will - into a less general route with a shorter subnet mask. This can be (but does not have to be) performed by supernetting , which is basically a play on the whole classful route categories. When you choose to present a route that falls into one of the old alphabetical classes (A,B,C), but that route has a subnet mask that is shorter than indicated by that class, you are performing supernetting. Supernetting can be used as a specific kind of summarization. But summarization need not be performed by supernetting. But, sir, exactly when the hell did I imply that summarization always equated to supernetting? Only in my network would that be the case, because of the particular addresing scheme in use. Why won't we take this off-line, and just deal with each other directly from now on, buddy? No need to waste everybody else's time with this. Donald B Johnson jr wrote in message news:[EMAIL PROTECTED]... Forget the spelling: guantlet is down why don't you tell us the difference between summarization and supernetting. i'll bet you can't - Original Message - From: nrf To: Sent: Friday, August 03, 2001 2:19 PM Subject: Re: Just how important is route summarization in typical [7:14841] Hello- who the hell is the Delhi lama? It's the Dalai Lama, dumb-ass. It's Elvis, not elvs. Go back to grade school and learn how to spell. Donald B Johnson jr wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Its nothing but morons for a fifty mile radius from you, and you can't use summarization because only you, the delhi-lama and elvs could ever understand it. What does this have to do with the original question. Why don't you just type up a spread sheet and paste it on the side of the router, they will never know if the routes are summarized. This is one of the most moronic discussions on this lists in a long time. Why are they just having a problem with summarization, if they are so dumb. Oh and technically speaking supernets and summarization are two different things but I was hoping that delhi-lama elvis would knock ya off your high horse. I'll throw you a bone there biff, Not All Summarized routes are Supernets. Call me at 3am when you figure it out. - Original Message - From: nrf To: Sent: Friday, August 03, 2001 11:26 AM Subject: Re: Just how important is route summarization in typical [7:14814] My biggest problem with summarization so far: Ring-Ring-Ring - my cellphone goes off at 3AM, I'm rudely awakened and blearily reach for it: Hello? - I say weakly Hey boss, I'm on the office router, and I can't see all the routes!!! Well, that's probably because I summarized it, and you can only see the supernets Uhh, boss, what's summarization? What's a supernet? That's my biggest problem with summarization right there, it requires a higher level of understanding than my guys have. I got a bunch of (very) junior guys who know how to get into the router, they know how to do show ip route , and they know how to ping, and that's pretty much about it as far as networks go.They don't know the intricacies of subnetting, supernetting, blah blah blah, I don't have time to teach them, and quite frankly I don't think they want to know anyway (they're just NT admins, and that's what they want to spend their time doing). All they want, and all I want for them, is to be able to go to any router, and look for all the routes in the network, that's all. I suppose the presumption was that only I, or other skilled network guys were taking care of this network, and this is not so. I hope everybody sees in this light why I have an objection of using it in my network. I am not particularly inclined to do anything even a little bit complex because I am not the one who is going to maintain it. Ultimately, it's a manageability thing. Howard C. Berkowitz wrote in message news:[EMAIL PROTECTED]... At 05:07 PM 8/2/2001 -0400, you wrote: Ah, but why stop at 3, why not 30 or 300 or 3000 disasters all at once? Reason being at some point it really is not cost-effective to try to engineer your systems to be even more safe, because the extra safety margin is not worth the massive amount of money you have to spend. So, goes to what I thought was my original question (but apparently it has been twisted around, so let me ask it again) - how large does your network have to grow before it really starts to benefit from summarization? As I'm sure we're all aware, summarization is
Re: Just how important is route summarization in t [7:14783]
[EMAIL PROTECTED] wrote: I agree with you, Howard. All the best practices I have ever learned have stated that route summarization should be avoided, and, if not possible, at least minimized. I think unless you have a large network with multiple AS's, route summarization should only be considered a temporary fix until a common protocol is chosen and can be implemented. I consider it to be along the lines of using Virtual Links. My .02c, Rob H. CCNP, CCDP, MCSE Where did you learn that summarization was to be kept to a minimum and was a temporary fix? That's crazy... Summarization is a GOOD thing. Virtual Links are for temporary use, but summarization is one of the MAIN advantages of using hierachical addressing!! Geez. I read your comment to many friends of mine including plenty of CCNP/CCDP/CCIEs and every one of them said this guy's crazy. I'm *not* saying you're crazy, but I would sincerely like to know where you read/learned that summarization should be avoided and is a temporary fix. Please tell me your sources. Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14808t=14783 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Just how important is route summarization in typical [7:14863]
as someone who once was in the position of managing help desk and system admins, I have to butt in and say that the toughest problem I had in that respect was getting people to think for themselves. I had employees whose answer to everything was to reformat the hard drive, or reboot the modem the net CSU's ) or worse yet come and ask me how to solve the problem ( why do I need you if I'm doing all the work anyway? ) it could well be that the subordinates in question are lacking clue of any kind. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of GB Sent: Friday, August 03, 2001 5:12 PM To: [EMAIL PROTECTED] Subject: Re: Just how important is route summarization in typical [7:14854] Just ignore him DJ, what he's trying to do is just retain his job security as head idiot. By telling his management that he is surrounded by a bunch of very junior NT admins that can't do anything without him, he tries to quanlify his value and necessity to the organization. What make an excellent manager is not one that can do everything, but teach difficult concepts effectively and delegate those responsibilities appropriately. CIO material this guy is definately not. As for working under this guy, how many of us would like to be greeted by Allright, punk-ass bitch what the hell do you not understand now?!?! as the beginning of his training sessions. I don't blame his very junior NT admins from trying to stay away as far as possible from this guy... - Original Message - From: Donald B Johnson jr To: Sent: Friday, August 03, 2001 2:38 PM Subject: Fw: Just how important is route summarization in typical [7:14842] I dont think this guy is stable. And it is still a moronic discussion. Who cares that he can't summarize because he is surronded by idiots. I mean am I missing something here. - Original Message - From: nrf To: Donald B Johnson jr Sent: Friday, August 03, 2001 2:05 PM Subject: Re: Just how important is route summarization in typical [7:14814] Allright, punk-ass bitch. You got a problem with me? Did I ruin your day? Why don't we meet somewhere and we'll settle it like men? Anytime, anyplace, bitch. - Original Message - From: Donald B Johnson jr To: nrf ; Sent: Friday, August 03, 2001 3:54 PM Subject: Re: Just how important is route summarization in typical [7:14814] Its nothing but morons for a fifty mile radius from you, and you can't use summarization because only you, the delhi-lama and elvs could ever understand it. What does this have to do with the original question. Why don't you just type up a spread sheet and paste it on the side of the router, they will never know if the routes are summarized. This is one of the most moronic discussions on this lists in a long time. Why are they just having a problem with summarization, if they are so dumb. Oh and technically speaking supernets and summarization are two different things but I was hoping that delhi-lama elvis would knock ya off your high horse. I'll throw you a bone there biff, Not All Summarized routes are Supernets. Call me at 3am when you figure it out. - Original Message - From: nrf To: Sent: Friday, August 03, 2001 11:26 AM Subject: Re: Just how important is route summarization in typical [7:14814] My biggest problem with summarization so far: Ring-Ring-Ring - my cellphone goes off at 3AM, I'm rudely awakened and blearily reach for it: Hello? - I say weakly Hey boss, I'm on the office router, and I can't see all the routes!!! Well, that's probably because I summarized it, and you can only see the supernets Uhh, boss, what's summarization? What's a supernet? That's my biggest problem with summarization right there, it requires a higher level of understanding than my guys have. I got a bunch of (very) junior guys who know how to get into the router, they know how to do show ip route , and they know how to ping, and that's pretty much about it as far as networks go.They don't know the intricacies of subnetting, supernetting, blah blah blah, I don't have time to teach them, and quite frankly I don't think they want to know anyway (they're just NT admins, and that's what they want to spend their time doing). All they want, and all I want for them, is to be able to go to any router, and look for all the routes in the network, that's all. I suppose the presumption was that only I, or other skilled network guys were taking care of this network, and this is not so. I hope everybody sees in this light why I have an objection of using it in my network. I am not particularly inclined to do anything even a little bit complex because I am not the one who is going to maintain it. Ultimately
Re: Just how important is route summarization in typical [7:14868]
Hey, I think I'm a very mellow person, until I get crossed. I invite you to check the archives and see for yourself who fired the first shot, Mr. Johnson or me. I'll let your comment about the 'head idiot' pass, but as I've stated previously, I have asked management several times to hire some better guys, and have been rebuffed each time. You know how it is now, IT budgets aren't exactly flush with cash.Besides, my staff has pretty much made it clear to me that they don't really want to know networks, as they are perfectly happy being Microsofties, that's what they know how to do, and that's all they really want to do. They grumble whenever they have to get into the router at all, and they try to leave it as soon as they are sure that it's not the system that is causing the problems. And no, when I greet my staff I am nothing if not polite to a fault. But then of course, I don't have my staff insulting and taunting me (as Mr. Johnson felt the need to do). Cheers GB wrote in message news:[EMAIL PROTECTED]... Just ignore him DJ, what he's trying to do is just retain his job security as head idiot. By telling his management that he is surrounded by a bunch of very junior NT admins that can't do anything without him, he tries to quanlify his value and necessity to the organization. What make an excellent manager is not one that can do everything, but teach difficult concepts effectively and delegate those responsibilities appropriately. CIO material this guy is definately not. As for working under this guy, how many of us would like to be greeted by Allright, punk-ass bitch what the hell do you not understand now?!?! as the beginning of his training sessions. I don't blame his very junior NT admins from trying to stay away as far as possible from this guy... - Original Message - From: Donald B Johnson jr To: Sent: Friday, August 03, 2001 2:38 PM Subject: Fw: Just how important is route summarization in typical [7:14842] I dont think this guy is stable. And it is still a moronic discussion. Who cares that he can't summarize because he is surronded by idiots. I mean am I missing something here. - Original Message - From: nrf To: Donald B Johnson jr Sent: Friday, August 03, 2001 2:05 PM Subject: Re: Just how important is route summarization in typical [7:14814] Allright, punk-ass bitch. You got a problem with me? Did I ruin your day? Why don't we meet somewhere and we'll settle it like men? Anytime, anyplace, bitch. - Original Message - From: Donald B Johnson jr To: nrf ; Sent: Friday, August 03, 2001 3:54 PM Subject: Re: Just how important is route summarization in typical [7:14814] Its nothing but morons for a fifty mile radius from you, and you can't use summarization because only you, the delhi-lama and elvs could ever understand it. What does this have to do with the original question. Why don't you just type up a spread sheet and paste it on the side of the router, they will never know if the routes are summarized. This is one of the most moronic discussions on this lists in a long time. Why are they just having a problem with summarization, if they are so dumb. Oh and technically speaking supernets and summarization are two different things but I was hoping that delhi-lama elvis would knock ya off your high horse. I'll throw you a bone there biff, Not All Summarized routes are Supernets. Call me at 3am when you figure it out. - Original Message - From: nrf To: Sent: Friday, August 03, 2001 11:26 AM Subject: Re: Just how important is route summarization in typical [7:14814] My biggest problem with summarization so far: Ring-Ring-Ring - my cellphone goes off at 3AM, I'm rudely awakened and blearily reach for it: Hello? - I say weakly Hey boss, I'm on the office router, and I can't see all the routes!!! Well, that's probably because I summarized it, and you can only see the supernets Uhh, boss, what's summarization? What's a supernet? That's my biggest problem with summarization right there, it requires a higher level of understanding than my guys have. I got a bunch of (very) junior guys who know how to get into the router, they know how to do show ip route , and they know how to ping, and that's pretty much about it as far as networks go.They don't know the intricacies of subnetting, supernetting, blah blah blah, I don't have time to teach them, and quite frankly I don't think they want to know anyway (they're just NT admins, and that's what they want to spend their time doing). All they want, and all I want for them, is to be able to go to any router, and look for all the routes
RE: Just how important is route summarization in typical [7:14869]
Mike, yours is about the best message in this thread to use as a start point for some random thoughts. seems to me that there are architectures and network sizes that do and do not lend themselves to summarization. for example, in the typical small network hub and spoke setup, it's questionable whether or not routing protocols are even required. static routes or Cisco On Demand Routing are probably more than sufficient. yes the books all say that static routing doesn't scale. but consider the company that starts with a central site and 10 branch offices, and adds a branch every six months. shared services are all at the hub. the branches don't care about eachother's existence. most of us throw EIGRP onto the routers and have done with it. but in truth, it is unnecessary. there isn't a lot of work here, and this is probably good for as long as the model applies. in the case where a new domain is added into an existing network, summarization can be quite useful. for example, I am working with a customer who is setting up an RLAN as a telecommute network ( DSL at the user side, ATM at the host side )under the original design, there would have been one net for each wan link, and one net for each home user device, /30s in all cases. rather than advertise hundreds of /30's we planned on summarization, advertising only two routes into the corporate domain. another interesting case I came across at another customer site. EIGRP everywhere in a campus environment. multiple buildings, half of which were connected via fiber and switches, the other half of which were connected by T1's and routers. discontiguous subnets everywhere. we determined that there were two entry points from the routed domains into the corporate network, and we figured we could summarize at the classful boundary at each of these entry points, and advertise those summaries to the appropriate domain. I'll have to look up my notes on the topology in this case. it made sense to summarize at the time. what I am getting at is that topology can be the main driver in determining the usefulness of summarization. since the question was asked, I am assuming that the asker works in an environment where summarization is possible and makes sense ( except for the issue of the clueless subordinates, but that's another story. good post, Mike. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Thursday, August 02, 2001 5:19 PM To: [EMAIL PROTECTED] Subject: Re: Just how important is route summarization in typical [7:14734] I guess (to flip your question around) are there any cons to using summarization? You can't argue that it's extra administration is a con because the basis of your argument is that the network is rather small, so using summarization where it can be used takes literally seconds to put in place, and needs no troubleshooting. So, IMHO, the pros of summarization always outweighs the cons (none). But to deal more directly with your questions, let's start at the smallest level, 2 routers. With two routers (connected by a common network or a point to point link) summarization really has no place. If you look at 3 routers in the following layout: LAN A -- R1 -- LAN B -- R2 -- LAN C -- R3 -- LAN D In this scenario, it's possible that the connection between R2 and R3 could fail or change, but if R2 were summarizing to R1, R1 wouldn't have to be bothered by any difficulties on LAN C. Although the amount of CPU time or memory on R1 that is saved in this example is neglegible, it can be said that any CPU or memory that is saved is 0. The same could be said about summarizing on the link from R2 to R3 where problems on LAN B. Therefore, the 2 seconds it took to summarize on both interfaces of R2 yields some amount of CPU time and memory that is not wasted on R1 and R3, and therefore is a good thing, no matter how small. I would them extend this logic to more routers. You could even take the time to examine different partial- or full-mesh designs, but summarization really kicks in when there are networks that are more than 1 hop away that could be affected by routing updates triggered by a given LAN or WAN link, etc... So again, IMHO, any benefit in CPU and memory usage is 0 and therefore makes summarization worthwhile. So my answer to the cost-benefit is that there is virtually no cost yet a guaranteed benefit, so anything network with more than 1 hop from any given router can benefit from summarization... I gotta say (just now re-reading your cons), 1st) suboptimal routing shouldn't be a side effect of summarization. If the network is setup hierarchical (sp?), then you could summarize on virtually every router and it would never yield a suboptimal path. 2nd) Pain in the posterior to configure and maintain? Takes seconds to configure, and virtually no maintenance. 3rd) Inability to see your whole network from any router? Do you mean picking a router
Re: Just how important is route summarization in typical [7:14835]
Well, it's one thing to write network documentation. It's an entirely different thing for your guys to actually read it. I'm dealing with guys who are pretty set in their ways. mbaker2507 wrote in message news:[EMAIL PROTECTED]... Isn't this what network documentation is for? If people can go to a book and see what various show ... outputs should be (at least the important ones, like show ip route) then you can keep your beauty sleep. Mark Baker CCNP -Original Message- From: nrf [SMTP:[EMAIL PROTECTED]] Sent: Friday, August 03, 2001 2:27 PM To: [EMAIL PROTECTED] Subject: Re: Just how important is route summarization in typical [7:14814] My biggest problem with summarization so far: Ring-Ring-Ring - my cellphone goes off at 3AM, I'm rudely awakened and blearily reach for it: Hello? - I say weakly Hey boss, I'm on the office router, and I can't see all the routes!!! Well, that's probably because I summarized it, and you can only see the supernets Uhh, boss, what's summarization? What's a supernet? That's my biggest problem with summarization right there, it requires a higher level of understanding than my guys have. I got a bunch of (very) junior guys who know how to get into the router, they know how to do show ip route , and they know how to ping, and that's pretty much about it as far as networks go.They don't know the intricacies of subnetting, supernetting, blah blah blah, I don't have time to teach them, and quite frankly I don't think they want to know anyway (they're just NT admins, and that's what they want to spend their time doing). All they want, and all I want for them, is to be able to go to any router, and look for all the routes in the network, that's all. I suppose the presumption was that only I, or other skilled network guys were taking care of this network, and this is not so. I hope everybody sees in this light why I have an objection of using it in my network. I am not particularly inclined to do anything even a little bit complex because I am not the one who is going to maintain it. Ultimately, it's a manageability thing. Howard C. Berkowitz wrote in message news:[EMAIL PROTECTED]... At 05:07 PM 8/2/2001 -0400, you wrote: Ah, but why stop at 3, why not 30 or 300 or 3000 disasters all at once? Reason being at some point it really is not cost-effective to try to engineer your systems to be even more safe, because the extra safety margin is not worth the massive amount of money you have to spend. So, goes to what I thought was my original question (but apparently it has been twisted around, so let me ask it again) - how large does your network have to grow before it really starts to benefit from summarization? As I'm sure we're all aware, summarization is not all good, there are some bad points to it - the biggest being that it is just simply harder to troubleshoot a summarized network (because I can't see all the routes from all my routers). That puzzles me. I find summarization makes it easier to troubleshoot -- binary search versus linear search, if you will. By the way, I worked in the oil field for 9 years, and it's pretty dangerous. I've known people that died, and using systems that certainly were not engineered to take 3 disasters at once. Bill Pearch wrote in message news:[EMAIL PROTECTED]... Yes! An oil field engineer summed it up this way: When designing something, design it so three disasters have to happen at the same time before someone gets killed. I hate it when networks just happen. TTFN, Bill -Original Message- From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]] Sent: Thursday, August 02, 2001 12:13 PM To: [EMAIL PROTECTED] Subject: Re: Just how important is route summarization in typical [7:14700] In our industry, we assume something is going to wrong and plan for it. We plan how to minimize the affects of a link going down. My $0.0002 Priscilla Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14835t=14835 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Just how important is route summarization in typical [7:14836]
Its nothing but morons for a fifty mile radius from you, and you can't use summarization because only you, the delhi-lama and elvs could ever understand it. What does this have to do with the original question. Why don't you just type up a spread sheet and paste it on the side of the router, they will never know if the routes are summarized. This is one of the most moronic discussions on this lists in a long time. Why are they just having a problem with summarization, if they are so dumb. Oh and technically speaking supernets and summarization are two different things but I was hoping that delhi-lama elvis would knock ya off your high horse. I'll throw you a bone there biff, Not All Summarized routes are Supernets. Call me at 3am when you figure it out. - Original Message - From: nrf To: Sent: Friday, August 03, 2001 11:26 AM Subject: Re: Just how important is route summarization in typical [7:14814] My biggest problem with summarization so far: Ring-Ring-Ring - my cellphone goes off at 3AM, I'm rudely awakened and blearily reach for it: Hello? - I say weakly Hey boss, I'm on the office router, and I can't see all the routes!!! Well, that's probably because I summarized it, and you can only see the supernets Uhh, boss, what's summarization? What's a supernet? That's my biggest problem with summarization right there, it requires a higher level of understanding than my guys have. I got a bunch of (very) junior guys who know how to get into the router, they know how to do show ip route , and they know how to ping, and that's pretty much about it as far as networks go.They don't know the intricacies of subnetting, supernetting, blah blah blah, I don't have time to teach them, and quite frankly I don't think they want to know anyway (they're just NT admins, and that's what they want to spend their time doing). All they want, and all I want for them, is to be able to go to any router, and look for all the routes in the network, that's all. I suppose the presumption was that only I, or other skilled network guys were taking care of this network, and this is not so. I hope everybody sees in this light why I have an objection of using it in my network. I am not particularly inclined to do anything even a little bit complex because I am not the one who is going to maintain it. Ultimately, it's a manageability thing. Howard C. Berkowitz wrote in message news:[EMAIL PROTECTED]... At 05:07 PM 8/2/2001 -0400, you wrote: Ah, but why stop at 3, why not 30 or 300 or 3000 disasters all at once? Reason being at some point it really is not cost-effective to try to engineer your systems to be even more safe, because the extra safety margin is not worth the massive amount of money you have to spend. So, goes to what I thought was my original question (but apparently it has been twisted around, so let me ask it again) - how large does your network have to grow before it really starts to benefit from summarization? As I'm sure we're all aware, summarization is not all good, there are some bad points to it - the biggest being that it is just simply harder to troubleshoot a summarized network (because I can't see all the routes from all my routers). That puzzles me. I find summarization makes it easier to troubleshoot -- binary search versus linear search, if you will. By the way, I worked in the oil field for 9 years, and it's pretty dangerous. I've known people that died, and using systems that certainly were not engineered to take 3 disasters at once. Bill Pearch wrote in message news:[EMAIL PROTECTED]... Yes! An oil field engineer summed it up this way: When designing something, design it so three disasters have to happen at the same time before someone gets killed. I hate it when networks just happen. TTFN, Bill -Original Message- From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]] Sent: Thursday, August 02, 2001 12:13 PM To: [EMAIL PROTECTED] Subject: Re: Just how important is route summarization in typical [7:14700] In our industry, we assume something is going to wrong and plan for it. We plan how to minimize the affects of a link going down. My $0.0002 Priscilla Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14836t=14836 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Just how important is route summarization in typical [7:14629]
I thought somebody was going to talk about masking instabilities. But then that begs the question - in a typical enterprise network (therefore a small one of 100 routes or less), if you are suffering from routing instabilities, isn't your time better spent to try to figure out why your routes are so unstable and then remedying it rather than engaging in summarization in order to mask the instability. But the summarization localizes the instability and speeds the time to find the links that are flapping. If I cut myself, and the wound stops bleeding, I am still likely to put a dressing on it to keep it clean. A large percent of the time, if the wound was clean to begin with, it won't get infected whether I put the dressing on or not. There are certainly differences in local practice -- American medical personnel wipe an injection site with alcohol first, while Europeans generally don't -- and, for routine injections (i.e., not, say arterial or IV), there's no noticeable difference in infection rate. Summarization is what the IETF calls best current practice, because experience shows that it tends to avoid problems. One of the most important reasons is that it forces, if you will, infection controls onto your addressing plan. Hierarchical networks are much easier to expand if your network suddenly grows, which it may in a world of mergers and acquisitions. I always wear my seat belt. Oh...and as long as we're mentioning grails, I'm off to the IETF in London. Perhaps I should request that I be addressed as Arthur, King of the Britons, and that I am on a quest. Like I said previously, I completely agree that summarization is indeed very useful in large networks like NSP/ISP's or large enterprises (1000+ routes), for many reasons (better lookup performance, masking truly becomes useful because you can't be expected to fix all your flaky links in a huge network, etc.). But I would like to understand if summarization can be useful in a typical enterprise network ( wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Performance gains are only a small part of the picture... what is more important is enforcing a proper hierarchical addressing scheme that conceals routing instabilities from the network as a whole, and lessens the amount of routing update traffic propagated across the entire network. It's gotten to the point that Cisco-trained personnel treat summarization like the holy grail, and they go around trying to use summarization techniques wherever they can. A network always benefits from the consistent application of design goals. Summarization scales well because of the architecture which flows from a properly addressed network. I can't think of anyone outside of an SP network concerned with global routing table bloat that ever equates the benefits of summarization in terms of increased routing table lookup efficiency. The benefit is that flapping routes and their attendant update traffic are confined to a small manageable area. Not only does this preserve bw but it greatly aids in network management by narrowing the scope of the network that you need to troubleshoot. So, when I weigh the cons of suboptimal routing as well as the possibility of misconfiguration, I find it difficult to see why the typical enterprise would ever really want to do summarization, as the gains are miniscule at best. If the network architects can't properly summarize, there are bound to be bigger problems than what that particular misconfiguration will bring. We are not talking rocket science here, it is simple binary math. Best regards, Geoff Zinderdine CCNP MCP2K CCA MTS Communications Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14629t=14629 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Just how important is route summarization in typical [7:14622]
--- nrf wrote: I thought somebody was going to talk about masking instabilities. But then that begs the question - in a typical enterprise network (therefore a small one of 100 routes or less), if you are suffering from routing instabilities, isn't your time better spent to try to figure out why your routes are so unstable and then remedying it rather than engaging in summarization in order to mask the instability. There is no question begged. You make it sound like summarization is being used as a method to deal with a crisis. It is most emphatically not that. It is a network design principle/technique that can (among other things) reduce the impact of routing instability and isolate it so that you can deal with it effectively and quickly. Routing instability can be caused by hardware failure, not just configuration problems. No one goes around summarizing routes in the middle of an outage. Summarization is considered while designing and implementing the topology you have decided upon. Sound network designs should make sense, not just merely work because you can throw CPU/memory at them. Hierarchy simplifies understanding the network topology and actually aids in the sensible deployment of address space. What you are advocating is merely sloppy thinking that is excused only by its small scale: Close enough for government work. What happens if that enterprise succeeds and grows into a multinational with its own AS and countless branch offices. Heaven help you if you are the hapless engineer that has to renumber and redesign that klugey network that was built solely on expediency. Geoff. Like I said previously, I completely agree that summarization is indeed very useful in large networks like NSP/ISP's or large enterprises (1000+ routes), for many reasons (better lookup performance, masking truly becomes useful because you can't be expected to fix all your flaky links in a huge network, etc.). But I would like to understand if summarization can be useful in a typical enterprise network ( wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Performance gains are only a small part of the picture... what is more important is enforcing a proper hierarchical addressing scheme that conceals routing instabilities from the network as a whole, and lessens the amount of routing update traffic propagated across the entire network. It's gotten to the point that Cisco-trained personnel treat summarization like the holy grail, and they go around trying to use summarization techniques wherever they can. A network always benefits from the consistent application of design goals. Summarization scales well because of the architecture which flows from a properly addressed network. I can't think of anyone outside of an SP network concerned with global routing table bloat that ever equates the benefits of summarization in terms of increased routing table lookup efficiency. The benefit is that flapping routes and their attendant update traffic are confined to a small manageable area. Not only does this preserve bw but it greatly aids in network management by narrowing the scope of the network that you need to troubleshoot. So, when I weigh the cons of suboptimal routing as well as the possibility of misconfiguration, I find it difficult to see why the typical enterprise would ever really want to do summarization, as the gains are miniscule at best. If the network architects can't properly summarize, there are bound to be bigger problems than what that particular misconfiguration will bring. We are not talking rocket science here, it is simple binary math. Best regards, Geoff Zinderdine CCNP MCP2K CCA MTS Communications __ Do You Yahoo!? Make international calls for as low as $.04/minute with Yahoo! Messenger http://phonecard.yahoo.com/ [EMAIL PROTECTED] __ Do You Yahoo!? Make international calls for as low as $.04/minute with Yahoo! Messenger http://phonecard.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14622t=14622 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Just how important is route summarization in typical enterprise [7:14628]
I agree that route summarisation may not speed up route lookup much. But there's other far more valid reasons for doing it. The network I work with is not ISP size in terms of routes, but it's pretty big, with hundreds of geographically dispersed sites - without summarisation, we'd have thousands of routes. Here's some reasons why we summarise... mostly they would apply to smaller networks as well. If you summarise (sensibly), you can hide route flaps from a large part of the network. If an ethernet segment in Bourke falls over, the router in Broome really shouldn't have to care less. By summarising, you restrict the number of routers that have to recalculate routes, so routers spend less time thinking about how to route and more time forwarding packets (hopefully). If you summarise (sensibly), you can reduce the amount of route information in your routing tables. Forget routing lookup time - depending on your routing protocol, this can substantially reduce the amount of data that has to be transferred between routers (less overhead traffic), and reduce the amount of calculations the router has to do. Again - less time doing (and sending) background stuff, more time to route real data. If you summarise (sensibly), it's much easier to read the ip routing table - fewer pages of info to wade through :-) I tweaked the summarisation of our network several months ago. Previously, we had been having occasional problems that were usually being put down to OSPF recalculations (mostly erroneously, IMO, but it was creaking occasionally). Since summarisation was beefed up, there have been no problems (or maybe people just decided they couldn't point the finger at OSPF any more :-) JMcL -- Forwarded by Jenny Mcleod/NSO/CSDA on 02/08/2001 04:48 pm --- nrf @groupstudy.com on 02/08/2001 02:42:45 pm Please respond to nrf Sent by: [EMAIL PROTECTED] To: [EMAIL PROTECTED] cc: Subject: Just how important is route summarization in typical enterprise [7:14601] Hey all. I'm going to risk starting a flame war by asking the following: I've been struck by just how much importance Cisco courseware places on route summarization. For example, every student who goes through CCNP-level courseware learns about all the various kinds of summarization - OSPF area summarization, OSPF stubs, EIGRP summarization, etc. etc., and how it reduces the size of the route table, thereby improving router performance by speeding route lookup. It's gotten to the point that Cisco-trained personnel treat summarization like the holy grail, and they go around trying to use summarization techniques wherever they can. Yet, I seem to recall somebody wrote a book (I believe it was Berkowitz) that basically stated that the performance gains associated with reducing the route table via summarization is virtually nil in typical corporate networks, because the real delays were caused simply by the serialization time of sending packets over slow WAN links (T-1 and slower). Plus, with fast-switching and its cousins (optimum switching, MLS, etc.), route lookup isn't done all that often , so there is little lookup delay anyway.And besides, most corporate networks aren't very big - typically less than 100 route entries, so how much lookup delay could there be? So, when I weigh the cons of suboptimal routing as well as the possibility of misconfiguration, I find it difficult to see why the typical enterprise would ever really want to do summarization, as the gains are miniscule at best. Note, I know full well that ISP's/NSP's and very large enterprises (those having on the order of thousands of routes) do indeed benefit substantially from summarization. Of this I have no doubt. What I cannot see is why the typical enterprise would really want to use summarization techniques. Anybody have any thoughts on this? Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14628t=14628 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Just how important is route summarization in typical [7:14632]
Hey all. I'm going to risk starting a flame war by asking the following: A bit more precision. You have to consider more than one kind of performance. One is route lookup in the fast forwarding path, and the other is changing the routing table (possibly in the same processor that does forwarding, in a small network). With modern algorithms such as Cisco's patented trie or the Patricia trie, route lookup times do not increase appreciably with the number of routes. Memory increases, but lookup time much less so. The increases in load come from changes to the routing table and consequent changes to the FIB. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14632t=14632 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Just how important is route summarization in typical enterprise [7:14601]
Hey all. I'm going to risk starting a flame war by asking the following: I've been struck by just how much importance Cisco courseware places on route summarization. For example, every student who goes through CCNP-level courseware learns about all the various kinds of summarization - OSPF area summarization, OSPF stubs, EIGRP summarization, etc. etc., and how it reduces the size of the route table, thereby improving router performance by speeding route lookup. It's gotten to the point that Cisco-trained personnel treat summarization like the holy grail, and they go around trying to use summarization techniques wherever they can. Yet, I seem to recall somebody wrote a book (I believe it was Berkowitz) that basically stated that the performance gains associated with reducing the route table via summarization is virtually nil in typical corporate networks, because the real delays were caused simply by the serialization time of sending packets over slow WAN links (T-1 and slower). Plus, with fast-switching and its cousins (optimum switching, MLS, etc.), route lookup isn't done all that often , so there is little lookup delay anyway.And besides, most corporate networks aren't very big - typically less than 100 route entries, so how much lookup delay could there be? So, when I weigh the cons of suboptimal routing as well as the possibility of misconfiguration, I find it difficult to see why the typical enterprise would ever really want to do summarization, as the gains are miniscule at best. Note, I know full well that ISP's/NSP's and very large enterprises (those having on the order of thousands of routes) do indeed benefit substantially from summarization. Of this I have no doubt. What I cannot see is why the typical enterprise would really want to use summarization techniques. Anybody have any thoughts on this? Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14601t=14601 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Just how important is route summarization in typical [7:14612]
Performance gains are only a small part of the picture... what is more important is enforcing a proper hierarchical addressing scheme that conceals routing instabilities from the network as a whole, and lessens the amount of routing update traffic propagated across the entire network. It's gotten to the point that Cisco-trained personnel treat summarization like the holy grail, and they go around trying to use summarization techniques wherever they can. A network always benefits from the consistent application of design goals. Summarization scales well because of the architecture which flows from a properly addressed network. I can't think of anyone outside of an SP network concerned with global routing table bloat that ever equates the benefits of summarization in terms of increased routing table lookup efficiency. The benefit is that flapping routes and their attendant update traffic are confined to a small manageable area. Not only does this preserve bw but it greatly aids in network management by narrowing the scope of the network that you need to troubleshoot. So, when I weigh the cons of suboptimal routing as well as the possibility of misconfiguration, I find it difficult to see why the typical enterprise would ever really want to do summarization, as the gains are miniscule at best. If the network architects can't properly summarize, there are bound to be bigger problems than what that particular misconfiguration will bring. We are not talking rocket science here, it is simple binary math. Best regards, Geoff Zinderdine CCNP MCP2K CCA MTS Communications __ Do You Yahoo!? Make international calls for as low as $.04/minute with Yahoo! Messenger http://phonecard.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14612t=14612 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Just how important is route summarization in typical [7:14615]
Hey all. I'm going to risk starting a flame war by asking the following: I've been struck by just how much importance Cisco courseware places on route summarization. For example, every student who goes through CCNP-level courseware learns about all the various kinds of summarization - OSPF area summarization, OSPF stubs, EIGRP summarization, etc. etc., and how it reduces the size of the route table, thereby improving router performance by speeding route lookup. It's gotten to the point that Cisco-trained personnel treat summarization like the holy grail, and they go around trying to use summarization techniques wherever they can. Yet, I seem to recall somebody wrote a book (I believe it was Berkowitz) that basically stated that the performance gains associated with reducing the route table via summarization is virtually nil in typical corporate networks, because the real delays were caused simply by the serialization time of sending packets over slow WAN links (T-1 and slower). Plus, with fast-switching and its cousins (optimum switching, MLS, etc.), route lookup isn't done all that often , so there is little lookup delay anyway.And besides, most corporate networks aren't very big - typically less than 100 route entries, so how much lookup delay could there be? So, when I weigh the cons of suboptimal routing as well as the possibility of misconfiguration, I find it difficult to see why the typical enterprise would ever really want to do summarization, as the gains are miniscule at best. I do recommend summarizing as much as possible, without being compulsive about it, even in fairly small networks. But forwarding performance isn't the major motivation when you have, say, 500 routes or less. There are a number of good reasons for doing it. One is to enforce hierarchical design and efficient address space use. This will definitely be important if you ever need to justify assignments of public address space, and it tends to make life generally simpler. Hierarchy tends to localize the effects of mergers and divestitures. It can localize the effects of problems and simplify troubleshooting. It can ease your capacity planning. Summarization also tends to contain the effect of route flapping and similar instabilities, which can have an appreciable load on router processors, especially small ones. As far as your point about suboptimal routing, I find that this tends to be an issue only in the largest networks. The reality is that small networks -- and even large networks -- don't have huge numbers of alternate paths that could be found for optimality. In one 2500 router network I redesigned, only 400 routers routinely had alternate paths (i.e., not dial backup) they used. If anything, the discipline of a hierarchical address plan helps you catch configuration errors early in the process. Note, I know full well that ISP's/NSP's and very large enterprises (those having on the order of thousands of routes) do indeed benefit substantially from summarization. Of this I have no doubt. What I cannot see is why the typical enterprise would really want to use summarization techniques. Anybody have any thoughts on this? To paraphrase Thomas Jefferson (I think), the tree of enterprise network topology must periodically be watered by the blood of renumbering. Hierarchical addressing vastly reduces the amount of blood that must be spilled, along with other good practices. See RFC 2072. I'm off to the IETF and pre- and post-IETF meetings, so may not be posting much for the next 10-14 days. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14615t=14615 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Just how important is route summarization in typical [7:14617]
I thought somebody was going to talk about masking instabilities. But then that begs the question - in a typical enterprise network (therefore a small one of 100 routes or less), if you are suffering from routing instabilities, isn't your time better spent to try to figure out why your routes are so unstable and then remedying it rather than engaging in summarization in order to mask the instability. Like I said previously, I completely agree that summarization is indeed very useful in large networks like NSP/ISP's or large enterprises (1000+ routes), for many reasons (better lookup performance, masking truly becomes useful because you can't be expected to fix all your flaky links in a huge network, etc.). But I would like to understand if summarization can be useful in a typical enterprise network ( wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Performance gains are only a small part of the picture... what is more important is enforcing a proper hierarchical addressing scheme that conceals routing instabilities from the network as a whole, and lessens the amount of routing update traffic propagated across the entire network. It's gotten to the point that Cisco-trained personnel treat summarization like the holy grail, and they go around trying to use summarization techniques wherever they can. A network always benefits from the consistent application of design goals. Summarization scales well because of the architecture which flows from a properly addressed network. I can't think of anyone outside of an SP network concerned with global routing table bloat that ever equates the benefits of summarization in terms of increased routing table lookup efficiency. The benefit is that flapping routes and their attendant update traffic are confined to a small manageable area. Not only does this preserve bw but it greatly aids in network management by narrowing the scope of the network that you need to troubleshoot. So, when I weigh the cons of suboptimal routing as well as the possibility of misconfiguration, I find it difficult to see why the typical enterprise would ever really want to do summarization, as the gains are miniscule at best. If the network architects can't properly summarize, there are bound to be bigger problems than what that particular misconfiguration will bring. We are not talking rocket science here, it is simple binary math. Best regards, Geoff Zinderdine CCNP MCP2K CCA MTS Communications __ Do You Yahoo!? Make international calls for as low as $.04/minute with Yahoo! Messenger http://phonecard.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=14617t=14617 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
ospf summarization !! [7:9418]
Yes. You can use the 'area x range etc etc' command on an ABR to summarise in either direction. To summarise backbone routes to a non-backbone area, its just 'area 0 range x.x.x.x x.x.x.x'. JMcL -- Forwarded by Jenny Mcleod/NSO/CSDA on 25/06/2001 01:42 pm --- Jeongwoo Park @groupstudy.com on 22/06/2001 06:37:27 am Please respond to Jeongwoo Park Sent by: [EMAIL PROTECTED] To: [EMAIL PROTECTED] cc: Subject: ospf summarization !! [7:9418] Hi all I know that we can summarize routes from non-backbone area to backbone area. But could we do the other way around? Jeongwoo JP Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9725t=9418 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
ospf summarization !! [7:9418]
Hi all I know that we can summarize routes from non-backbone area to backbone area. But could we do the other way around? Jeongwoo JP Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9418t=9418 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF summarization !! [7:9418]
IIRC, stub areas only receive inter-area summary routes and default routes? -Ej -Original Message- From: Jeongwoo Park [mailto:[EMAIL PROTECTED]] Sent: Thursday, June 21, 2001 4:37 PM To: [EMAIL PROTECTED] Subject: ospf summarization !! [7:9418] Hi all I know that we can summarize routes from non-backbone area to backbone area. But could we do the other way around? Jeongwoo JP Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9430t=9418 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Generic Summarization Planning Question [7:2952]
geez, that's a lot of questions. my attempts at answers in-line - Original Message - From: Murphy, Brennan To: Sent: Wednesday, May 02, 2001 1:48 PM Subject: Generic Summarization Planning Question [7:2952] I am curious about best practices concerning subnetting a class B address for a large enterprise network. If a company had 4 data centers spread throughout the globe, for example: SanFran Austin London Sydney One might chop the class B into 4 parts and if need be, reserve some space for growth. But what if each site also maintained an Internet Presence and Divide the class B space into summarizable sections that provided for both the growth of the data center proper *and* (the tricky part) all of the spokes that would come off of that data center. That way, the interconnections between the data centers could be summarized. You'd definitely want to use a RP that allowed for VLSM. Also reserve a block of each allocated data center 'summary' to use for small subnets (30 bit masks) for serial links, and for things like remote access and the WAN backbone and DMZs and loopback addresses and other miscellanity. had 5 or 6 external subnets being advertised via BGP. Would it make sense to re-do the subnetting so that all internal addressing was contiguous and all external addressing was contiguous? This way, You only get to advertise your public block with one AS, so unless you were using some other registered address space (which is frowned upon if you already have a big registered block), you'd set up iBGP internally and (probably) set the Internet access routers so that you didn't advertise yourself as a transit area. If you're using private B addressing, then your external doesn't matter because you'd have to use NAT anyway. I suppose that if you could afford it, you could have both internal and external links between the data centers so that you could use iBGP on the outside if a local data center lost its Internet connection you could ride it on the outside of the firewall, but that is a pretty far-fetched idea. There are better solutions than that. all internal addressing could be summarized with relatively few statements, and external nets as well. Does this sound reasonable? I've been Take a look at some case studies - good address design and allocation is one of the trickiest but most fulfilling skills that a Network Engineer can have, especially if it can be done well. With private address space, though, that skill has been diminished because we tend to throw caution to the wind and say Aww, if I run out of space in 172.16, I can use 172.17 browsing the CID book and other documents but havent come across anything that seems to address these concerns. Or would it just be better to make sure that all nets both internal/external are contiguous for a particular data center? Just wondering if anyone has been through this Your distinction between internal and external is interesting - I'm assuming that you mean inside the firewall and outside the firewall. Most firewalls don't pass routing protocol, which makes the distinction and the contiguous part moot. However, if you did expose your address block to the Internet (which we did at one company I worked for), it really didn't matter much that the Internet connection was part of the data center summarizable block. Actually, the danger there is the black hole phenomenon, where the summarized address 'eats' subnets that are not part of the block but still being used elsewhere in the enterprise but not behind the data center. It happens sometimes by accident, seldom by design. situation. Not sure if it would matter if OSPF or EIGRP is the IGP involved. I cc'ed Howard Berkowitz on this question -- Im told his first book is a great reference for this area. Maybe his response would spur me to purchase it. :-) Here's one of the best exercises you could do: o generate the scenario o start laying out subnets o see if you could summarize along major subnet boundaries with just the major sites. o start simple, with one Internet connection, then throw in one other Internet connection and see if you could figure out how to: 1. send users to the closest Internet connection 2. have users directed to the other Internet connection if their primary connection failed 3. prevent your network from becoming an Internet transit test your design for scaleability by o adding a 5th and 6th data center (aha! you were going to divide the B block into 4 parts???) o using more than the originally alloted address space for one data center due to spoke or campus growth (want to hear sysadmins complain? tell them that you underallocated address space in their site, and therefore they have to readdress) o create a complex (meshed) WAN behind one or more of the data centers and see how the addressing holds up. Hey, I have an idea.. use NAI's global network as your case study! ;-) -e- FAQ, list archives
Re: Route Summarization [7:1794]
OK, I think I got it. /15 doesn't make sense if I want to pick up just a 10.2.0.0 network because it would also pick up a 10.3.0.0 network. /16 will work if its the intent to summarize at 10.2.0.0, however that over summarizes if its not our intent to pick up 10.2.0.0 Therefore the three addresses: 10.2.1.0/24 10.2.2.0/24 10.2.3.0/24 can only be summarized as: 10.2.1.0/24 10.2.2.0/23 Thanks to all for your responses, they helped loads (especially if I got it right this time) Steve Howard C. Berkowitz wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I want to summarize three addresses within an OSPF area: 10.2.1.0/24 10.2.2.0/24 10.2.3.0/24 Converting to binary, I see the 15th bit is the highest order bit the three addresses have in common. From that I see the summary address is 10.2.0.0. What I don't understand is why the subnet mask is 16bits. To me it looks like it should be 15. Thanks, Steve There's a widespread and unfortunate belief that summarization is OK if it includes a list of addresses, even if it picks up addresses not included in the list. True, you can probably get away with that in many enterprise situations, but it can be catastrophic in the Internet. As I interpret the problem, the minimum number of addresses that can be created from your example are: 10.2.1.0/24 10.2.2.0/23 You can't do the /22, because it would pick up 10.2.0.0/24, which isn't part of the list. /15 or /16 make no sense. Converting the third octet to binary: 10.2.0.0/2400 00 10.2.1.0/2400 01 10.2.2.0/2400 10 10.2.3.0/2400 11 ^^ ^^ 111222 22 789012 34 FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=1864t=1794 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Route Summarization [7:1794]
I would think your mask would be more like /22 than /15 Do you really want to summarize at the /15 boundary? 10.0.0.0/15 might be it. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Stephen Alston Sent: Tuesday, April 24, 2001 6:07 PM To: [EMAIL PROTECTED] Subject:Route Summarization [7:1794] I want to summarize three addresses within an OSPF area: 10.2.1.0/24 10.2.2.0/24 10.2.3.0/24 Converting to binary, I see the 15th bit is the highest order bit the three addresses have in common. From that I see the summary address is 10.2.0.0. What I don't understand is why the subnet mask is 16bits. To me it looks like it should be 15. Thanks, Steve FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=1796t=1794 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Route Summarization [7:1794]
Thanks Chuck, I think the number of bits in the mask equals the number of highest order bits the addresses have in common. By highest order bit, does that mean a bit set to 1? As for the mask being 16, that's what the approved solution for a virtual lab says. It is possible the solution is wrong. At any rate, it has me confused. Steve Chuck Larrieu wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I would think your mask would be more like /22 than /15 Do you really want to summarize at the /15 boundary? 10.0.0.0/15 might be it. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Stephen Alston Sent: Tuesday, April 24, 2001 6:07 PM To: [EMAIL PROTECTED] Subject: Route Summarization [7:1794] I want to summarize three addresses within an OSPF area: 10.2.1.0/24 10.2.2.0/24 10.2.3.0/24 Converting to binary, I see the 15th bit is the highest order bit the three addresses have in common. From that I see the summary address is 10.2.0.0. What I don't understand is why the subnet mask is 16bits. To me it looks like it should be 15. Thanks, Steve FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=1798t=1794 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Route Summarization [7:1794]
Actually, the 22nd bit is the highest common bit. 10.2.0001.0 10.2.0010.0 10.2.0011.0 The longest summary for this would be 10.2.0.0 /22 Summarizing the range 10.2.0.0 thru 10.2.3.255 Stephen Alston wrote: I want to summarize three addresses within an OSPF area: 10.2.1.0/24 10.2.2.0/24 10.2.3.0/24 Converting to binary, I see the 15th bit is the highest order bit the three addresses have in common. From that I see the summary address is 10.2.0.0. What I don't understand is why the subnet mask is 16bits. To me it looks like it should be 15. Thanks, Steve FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=1808t=1794 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Route Summarization [7:1794]
I want to summarize three addresses within an OSPF area: 10.2.1.0/24 10.2.2.0/24 10.2.3.0/24 Converting to binary, I see the 15th bit is the highest order bit the three addresses have in common. From that I see the summary address is 10.2.0.0. What I don't understand is why the subnet mask is 16bits. To me it looks like it should be 15. Thanks, Steve There's a widespread and unfortunate belief that summarization is OK if it includes a list of addresses, even if it picks up addresses not included in the list. True, you can probably get away with that in many enterprise situations, but it can be catastrophic in the Internet. As I interpret the problem, the minimum number of addresses that can be created from your example are: 10.2.1.0/24 10.2.2.0/23 You can't do the /22, because it would pick up 10.2.0.0/24, which isn't part of the list. /15 or /16 make no sense. Converting the third octet to binary: 10.2.0.0/2400 00 10.2.1.0/2400 01 10.2.2.0/2400 10 10.2.3.0/2400 11 ^^ ^^ 111222 22 789012 34 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=1814t=1794 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Route Summarization [7:1794]
I want to summarize three addresses within an OSPF area: 10.2.1.0/24 10.2.2.0/24 10.2.3.0/24 Converting to binary, I see the 15th bit is the highest order bit the three addresses have in common. From that I see the summary address is 10.2.0.0. What I don't understand is why the subnet mask is 16bits. To me it looks like it should be 15. Thanks, Steve Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=1794t=1794 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Question regarding summarization and etc..
hi all: I need to know 1.how to summarize 1.1.0.0/16,1.3.0.0/16,1.0.3.0/23 and 1.0.16.0/23 2.when troublrshooting a serial interface you encounter the statement loop-up on the interface ,what does this mean. Thanks in Advance. Almazi CCNP _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Question regarding summarization and etc..
Without summarizing space outside of these blocks you can't. Readdressing is the next best option. --- Almazi Rashid [EMAIL PROTECTED] wrote: hi all: I need to know 1.how to summarize 1.1.0.0/16,1.3.0.0/16,1.0.3.0/23 and 1.0.16.0/23 2.when troublrshooting a serial interface you encounter the statement loop-up on the interface ,what does this mean. Thanks in Advance. Almazi CCNP _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] = Robert Padjen __ Do You Yahoo!? Yahoo! Auctions - Buy the things you want at great prices. http://auctions.yahoo.com/ _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
