RE: OSPF Virtual Links [7:60379]
Hi Matthew, You must always specify the transit area when configuring a virtual link. So use following command on both area border routers: area transit-area virtual-link ip-address The configs on page 310 are not correct, since the transit area in the picture seems to be area 1. Moreover area 1 stub should be removed from the config. Configs should be like this: Router Jack interface loopback 0 ip address 10.10.10.33 255.255.255.0 router ospf 100 network 172.16.20.128 0.0.0.7 area 0 network 172.16.20.8 0.0.0.7 area 1 area 1 virtual-link 10.10.10.30 Router Darius = interface loopback 0 ip address 10.10.10.30 255.255.255.0 router ospf 100 network 172.16.20.32 0.0.0.7 area 5 network 172.16.20.64 0.0.0.7 area 1 area 1 virtual-link 10.10.10.33 Actually I'm trying to find an errata for the CCNP Routing Exam Certification Guide. I couldn't find it on the Cisco Press web site. Does anyone have an errata for this routing certification guide? Thanks, Eric Brouwers Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=61304t=60379 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF Virtual Links [7:60379]
Hi all, I am studying the Cisco text CCNP Routing Exam Certification Guide and on page 310 there is an example configuration: Router Jack interface loopback 0 ip address 10.10.10.33 255.255.255.0 router ospf 100 network 172.16.20.128 0.0.0.7 area 0 network 172.16.20.8 0.0.0.7 area 1 area 0 range 172.16.20.128 255.255.255.192 area 1 stub area 1 default-cost 15 area 5 virtual-link 10.10.10.30 Router Darius loopback interface 0 ip address 10.10.10.30 255.255.255.0 ospf 100 network 172.16.20.32 0.0.0.7 area 5 network 172.16.20.64 0.0.0.7 area 1 area 5 virtual-link 10.0.0.33 I'm interested in lines 10 and 17. I thought the area-id specified is the transit area, whereas in the diagram over the page the transit area is area 1, and area 0 has a virtual link to area 5. However here they have the area-id as 5, and not 1 (I would have thought it was 1). Can anyone confirm whether the area-id is 1 or 5, and why? any help appreciated. Matthew. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=60379t=60379 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF Virtual-links [7:42565]
Thanks for the reply! Good point about the router ID. After the first response, I began playing with the OSPF router-id command, and subsequently discovered that the virtual-link must be defined as terminating at the router-id, and not the physical interface or in any specific area. As far as joining discontiguous nonzero areas, I would be interested to see the configs... -Jeremy -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Chuck Sent: Thursday, April 25, 2002 6:29 PM To: [EMAIL PROTECTED] Subject: Re: OSPF Virtual-links [7:42565] In the world of OSPF, the virtual link end points are the router RID's This is defined in the RFC. with virtual links, the hello packet has the V bit set to 1. I believe that the TTL of the IP packet transporting the VL hello is set to 255. In any case, virtual link hellos are forwarded until such time as they reach a router who meets the VL end point requirement or until they reach the end of the area over which the virtual link is to travel. I presume that virtual link packets do not wander aimlessly through an OSPF domain, but stop at the border of the defined transit area. So, in answer to your question, no, the termination point of the virtual link does not have to be an interface in area 0. in fact, virtual links can be used to join discontiguous non zero areas. There is an example of this in Terry Slattery's book Advanced IP Routing in Cisco Networks. HTH Jeremy wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... My question is regarding OSPF and virtual links. As you can see, I have created an area 23 between R2 and R3 such that R3 will need a virtual link defined in order to have a connection to Area 0. My question is, does R3 have to peer with an interface in R2 that is a member of area 0? I have noticed that if I put R2's loopback interface (which R3 is peering to) in area 23, it fails, whereas, if I move the interface to area 0, the virtual link comes up. Please take a look at the crude diagram below, or the attached visio for clarification. Please let me know your thoughts on this. Thanks again for all of your informed help (and I apologize if this appears to be a less-than-CCIE-caliber question). Topology map (excuse the crude map, if you have visio, check out the enclosed diagram: R5---R1 / \ /\ R4R2--R3 Router2: router ospf 10 area 23 virtual-link 130.10.23.3 network 130.10.2.2 0.0.0.0 area 0 (Loopback Interface) network 130.10.23.2 0.0.0.0 area 23 (Link to R3 Serial Interface (S1)) network 130.10.245.2 0.0.0.0 area 0 (Link to R5 Frame-Relay Interface (S0) [DR=R5]) Router3: router ospf 10 area 23 virtual-link 130.10.2.2 (Virtual link peering to Loopback on R2 (in area 0, does it have to be?) network 130.10.23.3 0.0.0.0 area 23 (link to R3 Serial Interface (S0)) Router4: router ospf 10 network 130.10.4.4 0.0.0.0 area 4 (Loopback Interface) network 130.10.245.4 0.0.0.0 area 0 (Link to R5 Frame-Relay Interface (S0) [DR=R5]) Router5: router ospf 10 network 130.10.5.5 0.0.0.0 area 5 network 130.10.245.5 0.0.0.0 area 0 neighbor 130.10.245.2 neighbor 130.10.245.4 BTW, anyone else taking the exam on April 30th? I am...heheh... [GroupStudy.com removed an attachment of type application/vnd] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=42657t=42565 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF Virtual-links [7:42565]
My question is regarding OSPF and virtual links. As you can see, I have created an area 23 between R2 and R3 such that R3 will need a virtual link defined in order to have a connection to Area 0. My question is, does R3 have to peer with an interface in R2 that is a member of area 0? I have noticed that if I put R2's loopback interface (which R3 is peering to) in area 23, it fails, whereas, if I move the interface to area 0, the virtual link comes up. Please take a look at the crude diagram below, or the attached visio for clarification. Please let me know your thoughts on this. Thanks again for all of your informed help (and I apologize if this appears to be a less-than-CCIE-caliber question). Topology map (excuse the crude map, if you have visio, check out the enclosed diagram: R5---R1 / \ / \ R4R2--R3 Router2: router ospf 10 area 23 virtual-link 130.10.23.3 network 130.10.2.2 0.0.0.0 area 0 (Loopback Interface) network 130.10.23.2 0.0.0.0 area 23 (Link to R3 Serial Interface (S1)) network 130.10.245.2 0.0.0.0 area 0 (Link to R5 Frame-Relay Interface (S0) [DR=R5]) Router3: router ospf 10 area 23 virtual-link 130.10.2.2 (Virtual link peering to Loopback on R2 (in area 0, does it have to be?) network 130.10.23.3 0.0.0.0 area 23 (link to R3 Serial Interface (S0)) Router4: router ospf 10 network 130.10.4.4 0.0.0.0 area 4 (Loopback Interface) network 130.10.245.4 0.0.0.0 area 0 (Link to R5 Frame-Relay Interface (S0) [DR=R5]) Router5: router ospf 10 network 130.10.5.5 0.0.0.0 area 5 network 130.10.245.5 0.0.0.0 area 0 neighbor 130.10.245.2 neighbor 130.10.245.4 BTW, anyone else taking the exam on April 30th? I am...heheh... [GroupStudy.com removed an attachment of type application/vnd] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=42565t=42565 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Virtual-links [7:42565]
I think the VL must be defined on both routers using each others RID not just any arbitraray interface) In your case maybe the time it worked just happened to be when you defined the link with the RID. Anthony Pace Jeremy wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... My question is regarding OSPF and virtual links. As you can see, I have created an area 23 between R2 and R3 such that R3 will need a virtual link defined in order to have a connection to Area 0. My question is, does R3 have to peer with an interface in R2 that is a member of area 0? I have noticed that if I put R2's loopback interface (which R3 is peering to) in area 23, it fails, whereas, if I move the interface to area 0, the virtual link comes up. Please take a look at the crude diagram below, or the attached visio for clarification. Please let me know your thoughts on this. Thanks again for all of your informed help (and I apologize if this appears to be a less-than-CCIE-caliber question). Topology map (excuse the crude map, if you have visio, check out the enclosed diagram: R5---R1 / \ /\ R4R2--R3 Router2: router ospf 10 area 23 virtual-link 130.10.23.3 network 130.10.2.2 0.0.0.0 area 0 (Loopback Interface) network 130.10.23.2 0.0.0.0 area 23 (Link to R3 Serial Interface (S1)) network 130.10.245.2 0.0.0.0 area 0 (Link to R5 Frame-Relay Interface (S0) [DR=R5]) Router3: router ospf 10 area 23 virtual-link 130.10.2.2 (Virtual link peering to Loopback on R2 (in area 0, does it have to be?) network 130.10.23.3 0.0.0.0 area 23 (link to R3 Serial Interface (S0)) Router4: router ospf 10 network 130.10.4.4 0.0.0.0 area 4 (Loopback Interface) network 130.10.245.4 0.0.0.0 area 0 (Link to R5 Frame-Relay Interface (S0) [DR=R5]) Router5: router ospf 10 network 130.10.5.5 0.0.0.0 area 5 network 130.10.245.5 0.0.0.0 area 0 neighbor 130.10.245.2 neighbor 130.10.245.4 BTW, anyone else taking the exam on April 30th? I am...heheh... [GroupStudy.com removed an attachment of type application/vnd] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=42572t=42565 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Virtual-links [7:42565]
In the world of OSPF, the virtual link end points are the router RID's This is defined in the RFC. with virtual links, the hello packet has the V bit set to 1. I believe that the TTL of the IP packet transporting the VL hello is set to 255. In any case, virtual link hellos are forwarded until such time as they reach a router who meets the VL end point requirement or until they reach the end of the area over which the virtual link is to travel. I presume that virtual link packets do not wander aimlessly through an OSPF domain, but stop at the border of the defined transit area. So, in answer to your question, no, the termination point of the virtual link does not have to be an interface in area 0. in fact, virtual links can be used to join discontiguous non zero areas. There is an example of this in Terry Slattery's book Advanced IP Routing in Cisco Networks. HTH Jeremy wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... My question is regarding OSPF and virtual links. As you can see, I have created an area 23 between R2 and R3 such that R3 will need a virtual link defined in order to have a connection to Area 0. My question is, does R3 have to peer with an interface in R2 that is a member of area 0? I have noticed that if I put R2's loopback interface (which R3 is peering to) in area 23, it fails, whereas, if I move the interface to area 0, the virtual link comes up. Please take a look at the crude diagram below, or the attached visio for clarification. Please let me know your thoughts on this. Thanks again for all of your informed help (and I apologize if this appears to be a less-than-CCIE-caliber question). Topology map (excuse the crude map, if you have visio, check out the enclosed diagram: R5---R1 / \ /\ R4R2--R3 Router2: router ospf 10 area 23 virtual-link 130.10.23.3 network 130.10.2.2 0.0.0.0 area 0 (Loopback Interface) network 130.10.23.2 0.0.0.0 area 23 (Link to R3 Serial Interface (S1)) network 130.10.245.2 0.0.0.0 area 0 (Link to R5 Frame-Relay Interface (S0) [DR=R5]) Router3: router ospf 10 area 23 virtual-link 130.10.2.2 (Virtual link peering to Loopback on R2 (in area 0, does it have to be?) network 130.10.23.3 0.0.0.0 area 23 (link to R3 Serial Interface (S0)) Router4: router ospf 10 network 130.10.4.4 0.0.0.0 area 4 (Loopback Interface) network 130.10.245.4 0.0.0.0 area 0 (Link to R5 Frame-Relay Interface (S0) [DR=R5]) Router5: router ospf 10 network 130.10.5.5 0.0.0.0 area 5 network 130.10.245.5 0.0.0.0 area 0 neighbor 130.10.245.2 neighbor 130.10.245.4 BTW, anyone else taking the exam on April 30th? I am...heheh... [GroupStudy.com removed an attachment of type application/vnd] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=42623t=42565 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: [Doyle on OSPF - Virtual Links [7:21658]
Chuck, Also remember that in a perfect world, virtual links are only meant to be a quick fix and, in most network designs, they are not an acceptable standard. My .02c, Rob H.NP, DP, blah,blah,blah. 1 of 48 Subj: RE: [Doyle on OSPF - Virtual Links [7:21658] Date: Tue, 2 Oct 2001 8:35:54 PM Eastern Daylight Time From: Chuck Larrieu To: [EMAIL PROTECTED] RFC 1793 discusses demand circuits in detail. I suspect but don not know for sure that virtual circuits are treated as demand circuits for a couple of reasons. A virtual circuit can traverse a bunch of routers from point of termination. The designers were sensitive to the added traffic that LSA's and hellos would add. Remember that the design work was done back in the days when a T1 was the greatest thing on earth, and 56K was common in WAN backbones. Also, it might be that the designers were thinking that virtual links might actually take place over dial up connections. for example, if I have a small dial up branch office in another state, I have them dial up to the nearest ( least costly ) branch office, rather than dial directly to my HQ site. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Curtis Call Sent: Tuesday, October 02, 2001 7:36 AM To: [EMAIL PROTECTED] Subject: Re: [Doyle on OSPF - Virtual Links [7:21658] This is referring to the fact that the virtual-link is being treated as a Demand Circuit. I don't believe that Doyle spoke much about this in his book, but I could be wrong. A Demand Circuit is used for low-bandwidth links such as ISDN to limit the uptime required for the link, this is done in two ways, first Hellos are suppressed between the two endpoints, and second LSAs are not sent when they expire, instead they are marked as DoNotAge LSAs which act just like they sound, they don't age. These two features are independent of each other, so for instance you could have a demand circuit that is suppressing Hellos, but isn't sending DoNotAge LSAs (so the LSAs will still need to be refreshed) or you could theoretically have a demand circuit that isn't suppressing Hellos, but is sending DoNotAge LSAs. In your situation, the link is suppressing Hellos as it states, but is not sending DoNotAge LSAs. This indicates that somewhere in your OSPF domain there is a router that doesn't support these LSAs, so the router is not allowed to generate them. It is a requirement for a router that supports virtual-links to always try to make it a demand circuit, so Cisco routers will always attempt to suppress Hellos over virtual links. For more info you could check out: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr _c/ipcprt2/1cfospf.htm#xtocid2773922 For even better, go to the source: http://www.ietf.org/rfc/rfc1793.txt Elmer Deloso wrote: Hi. On Routing TCP/IP's page 555 there is an output of show ip ospf virtual-link That has these two info: 1.DoNotAge LSA not allowed 2.Adjacency State FULL (Hello suppressed) Can someone please explain why these show up in the virtual link info? I must have missed the significance somehere in my studies because I can't explain these to myself. Thank you. Elmer Deloso Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=21838t=21658 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: [Doyle on OSPF - Virtual Links [7:21658]
funny how this quick fix holds a such a place of prominence in the standard ;- Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Wednesday, October 03, 2001 6:03 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: RE: [Doyle on OSPF - Virtual Links [7:21658] Chuck, Also remember that in a perfect world, virtual links are only meant to be a quick fix and, in most network designs, they are not an acceptable standard. My .02c, Rob H.NP, DP, blah,blah,blah. 1 of 48 Subj: RE: [Doyle on OSPF - Virtual Links [7:21658] Date: Tue, 2 Oct 2001 8:35:54 PM Eastern Daylight Time From: Chuck Larrieu To: [EMAIL PROTECTED] RFC 1793 discusses demand circuits in detail. I suspect but don not know for sure that virtual circuits are treated as demand circuits for a couple of reasons. A virtual circuit can traverse a bunch of routers from point of termination. The designers were sensitive to the added traffic that LSA's and hellos would add. Remember that the design work was done back in the days when a T1 was the greatest thing on earth, and 56K was common in WAN backbones. Also, it might be that the designers were thinking that virtual links might actually take place over dial up connections. for example, if I have a small dial up branch office in another state, I have them dial up to the nearest ( least costly ) branch office, rather than dial directly to my HQ site. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Curtis Call Sent: Tuesday, October 02, 2001 7:36 AM To: [EMAIL PROTECTED] Subject: Re: [Doyle on OSPF - Virtual Links [7:21658] This is referring to the fact that the virtual-link is being treated as a Demand Circuit. I don't believe that Doyle spoke much about this in his book, but I could be wrong. A Demand Circuit is used for low-bandwidth links such as ISDN to limit the uptime required for the link, this is done in two ways, first Hellos are suppressed between the two endpoints, and second LSAs are not sent when they expire, instead they are marked as DoNotAge LSAs which act just like they sound, they don't age. These two features are independent of each other, so for instance you could have a demand circuit that is suppressing Hellos, but isn't sending DoNotAge LSAs (so the LSAs will still need to be refreshed) or you could theoretically have a demand circuit that isn't suppressing Hellos, but is sending DoNotAge LSAs. In your situation, the link is suppressing Hellos as it states, but is not sending DoNotAge LSAs. This indicates that somewhere in your OSPF domain there is a router that doesn't support these LSAs, so the router is not allowed to generate them. It is a requirement for a router that supports virtual-links to always try to make it a demand circuit, so Cisco routers will always attempt to suppress Hellos over virtual links. For more info you could check out: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr _c/ipcprt2/1cfospf.htm#xtocid2773922 For even better, go to the source: http://www.ietf.org/rfc/rfc1793.txt Elmer Deloso wrote: Hi. On Routing TCP/IP's page 555 there is an output of show ip ospf virtual-link That has these two info: 1.DoNotAge LSA not allowed 2.Adjacency State FULL (Hello suppressed) Can someone please explain why these show up in the virtual link info? I must have missed the significance somehere in my studies because I can't explain these to myself. Thank you. Elmer Deloso Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=21992t=21658 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Doyle on OSPF - Virtual Links [7:21658]
Hi. On Routing TCP/IP's page 555 there is an output of show ip ospf virtual-link That has these two info: 1. DoNotAge LSA not allowed 2. Adjacency State FULL (Hello suppressed) Can someone please explain why these show up in the virtual link info? I must have missed the significance somehere in my studies because I can't explain these to myself. Thank you. Elmer Deloso Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=21658t=21658 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: [Doyle on OSPF - Virtual Links [7:21658]
This is referring to the fact that the virtual-link is being treated as a Demand Circuit. I don't believe that Doyle spoke much about this in his book, but I could be wrong. A Demand Circuit is used for low-bandwidth links such as ISDN to limit the uptime required for the link, this is done in two ways, first Hellos are suppressed between the two endpoints, and second LSAs are not sent when they expire, instead they are marked as DoNotAge LSAs which act just like they sound, they don't age. These two features are independent of each other, so for instance you could have a demand circuit that is suppressing Hellos, but isn't sending DoNotAge LSAs (so the LSAs will still need to be refreshed) or you could theoretically have a demand circuit that isn't suppressing Hellos, but is sending DoNotAge LSAs. In your situation, the link is suppressing Hellos as it states, but is not sending DoNotAge LSAs. This indicates that somewhere in your OSPF domain there is a router that doesn't support these LSAs, so the router is not allowed to generate them. It is a requirement for a router that supports virtual-links to always try to make it a demand circuit, so Cisco routers will always attempt to suppress Hellos over virtual links. For more info you could check out: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt2/1cfospf.htm#xtocid2773922 For even better, go to the source: http://www.ietf.org/rfc/rfc1793.txt Elmer Deloso wrote: Hi. On Routing TCP/IP's page 555 there is an output of show ip ospf virtual-link That has these two info: 1.DoNotAge LSA not allowed 2.Adjacency State FULL (Hello suppressed) Can someone please explain why these show up in the virtual link info? I must have missed the significance somehere in my studies because I can't explain these to myself. Thank you. Elmer Deloso -- [EMAIL PROTECTED] OSPF Practice Exam www.boson.com\tests\Advanced.htm Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=21665t=21658 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: [Re: [Doyle on OSPF - Virtual Links [7:21658]
Sorry, I meant to say that it is a requirement for a router that supports demand circuits to always attempt to make virtual- links act as demand circuits. It is a requirement for a router that supports virtual-links to always try to make it a demand circuit, so Cisco routers will always attempt to suppress Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=21684t=21658 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: [Doyle on OSPF - Virtual Links [7:21658]
Thanks for the reply and the CCO link. I do remember now reading up On this feature, now all I need to do is set this up at home using An ISDN simulator to see exactly what OSPF-related packets go through. Elmer -Original Message- From: Curtis Call [mailto:[EMAIL PROTECTED]] Sent: Tuesday, October 02, 2001 10:36 AM To: [EMAIL PROTECTED] Subject: Re: [Doyle on OSPF - Virtual Links [7:21658] This is referring to the fact that the virtual-link is being treated as a Demand Circuit. I don't believe that Doyle spoke much about this in his book, but I could be wrong. A Demand Circuit is used for low-bandwidth links such as ISDN to limit the uptime required for the link, this is done in two ways, first Hellos are suppressed between the two endpoints, and second LSAs are not sent when they expire, instead they are marked as DoNotAge LSAs which act just like they sound, they don't age. These two features are independent of each other, so for instance you could have a demand circuit that is suppressing Hellos, but isn't sending DoNotAge LSAs (so the LSAs will still need to be refreshed) or you could theoretically have a demand circuit that isn't suppressing Hellos, but is sending DoNotAge LSAs. In your situation, the link is suppressing Hellos as it states, but is not sending DoNotAge LSAs. This indicates that somewhere in your OSPF domain there is a router that doesn't support these LSAs, so the router is not allowed to generate them. It is a requirement for a router that supports virtual-links to always try to make it a demand circuit, so Cisco routers will always attempt to suppress Hellos over virtual links. For more info you could check out: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr _c/ipcprt2/1cfospf.htm#xtocid2773922 For even better, go to the source: http://www.ietf.org/rfc/rfc1793.txt Elmer Deloso wrote: Hi. On Routing TCP/IP's page 555 there is an output of show ip ospf virtual-link That has these two info: 1.DoNotAge LSA not allowed 2.Adjacency State FULL (Hello suppressed) Can someone please explain why these show up in the virtual link info? I must have missed the significance somehere in my studies because I can't explain these to myself. Thank you. Elmer Deloso -- [EMAIL PROTECTED] OSPF Practice Exam www.boson.com\tests\Advanced.htm Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=21706t=21658 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: [Doyle on OSPF - Virtual Links [7:21658]
RFC 1793 discusses demand circuits in detail. I suspect but don not know for sure that virtual circuits are treated as demand circuits for a couple of reasons. A virtual circuit can traverse a bunch of routers from point of termination. The designers were sensitive to the added traffic that LSA's and hellos would add. Remember that the design work was done back in the days when a T1 was the greatest thing on earth, and 56K was common in WAN backbones. Also, it might be that the designers were thinking that virtual links might actually take place over dial up connections. for example, if I have a small dial up branch office in another state, I have them dial up to the nearest ( least costly ) branch office, rather than dial directly to my HQ site. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Curtis Call Sent: Tuesday, October 02, 2001 7:36 AM To: [EMAIL PROTECTED] Subject: Re: [Doyle on OSPF - Virtual Links [7:21658] This is referring to the fact that the virtual-link is being treated as a Demand Circuit. I don't believe that Doyle spoke much about this in his book, but I could be wrong. A Demand Circuit is used for low-bandwidth links such as ISDN to limit the uptime required for the link, this is done in two ways, first Hellos are suppressed between the two endpoints, and second LSAs are not sent when they expire, instead they are marked as DoNotAge LSAs which act just like they sound, they don't age. These two features are independent of each other, so for instance you could have a demand circuit that is suppressing Hellos, but isn't sending DoNotAge LSAs (so the LSAs will still need to be refreshed) or you could theoretically have a demand circuit that isn't suppressing Hellos, but is sending DoNotAge LSAs. In your situation, the link is suppressing Hellos as it states, but is not sending DoNotAge LSAs. This indicates that somewhere in your OSPF domain there is a router that doesn't support these LSAs, so the router is not allowed to generate them. It is a requirement for a router that supports virtual-links to always try to make it a demand circuit, so Cisco routers will always attempt to suppress Hellos over virtual links. For more info you could check out: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr _c/ipcprt2/1cfospf.htm#xtocid2773922 For even better, go to the source: http://www.ietf.org/rfc/rfc1793.txt Elmer Deloso wrote: Hi. On Routing TCP/IP's page 555 there is an output of show ip ospf virtual-link That has these two info: 1.DoNotAge LSA not allowed 2.Adjacency State FULL (Hello suppressed) Can someone please explain why these show up in the virtual link info? I must have missed the significance somehere in my studies because I can't explain these to myself. Thank you. Elmer Deloso -- [EMAIL PROTECTED] OSPF Practice Exam www.boson.com\tests\Advanced.htm Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=21758t=21658 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
I need Help!!! Kindly help me(OSPF Virtual links) [7:674]
Hi Guys. I am configuring a virtual link between two OSPF routers but it is not working at all. I am sending u the configuration and diagram here;. Any help and pinters will be appreciated. Regards Shahid = Shahid Muhammad Shafi MSc Telecommunications Candidate University of Colorado Boulder BSEE(GIKI),MCSE+I,CNA,CCNA,CCNP Please help feed hungry people worldwide http://www.hungersite.com/ A small thing each of us can do to help others less fortunate than ourselves __ Do You Yahoo!? Get email at your own domain with Yahoo! Mail. http://personal.mail.yahoo.com/ Current configuration: ! version 10.2 service tcp-small-servers ! hostname catbert ! enable password lab ! ! interface Ethernet0 ip address 192.168.3.126 255.255.255.224 ! interface Ethernet1 ip address 192.168.3.62 255.255.255.224 ! interface Ethernet2 no ip address shutdown ! interface Ethernet3 ip address 192.168.21.120 255.255.255.0 ! interface Ethernet4 no ip address shutdown ! interface Ethernet5 no ip address shutdown ! interface Ethernet6 no ip address shutdown ! interface Ethernet7 no ip address shutdown ! interface Ethernet8 no ip address shutdown ! interface Ethernet9 ip address 192.168.90.1 255.255.255.0 shutdown ! interface Ethernet10 ip address 192.168.100.1 255.255.255.0 ! interface Ethernet11 ip address 192.168.80.1 255.255.255.0 ! interface Fddi0 no ip address no keepalive shutdown ! interface Hssi0 no ip address shutdown ! router ospf 1 network 192.168.3.32 0.0.0.31 area 2 network 192.168.3.96 0.0.0.31 area 2 ! no logging console ! ! line con 0 exec-timeout 0 0 password lab login line aux 0 password lab login transport input all line vty 0 4 password lab login ! end Current configuration: ! version 10.2 ! hostname breckenridge ! enable password lab ! ! interface Ethernet0 ip address 192.168.3.97 255.255.255.224 ! interface Ethernet1 ip address 192.168.3.94 255.255.255.224 ! router ospf 1 network 192.168.3.96 0.0.0.31 area 2 network 192.168.3.64 0.0.0.31 area 2 ! Current configuration: ! version 11.0 service udp-small-servers service tcp-small-servers ! hostname aspen ! enable password lab ! ! interface Loopback0 ip address 2.2.2.2 255.255.255.0 ! interface Ethernet0 no ip address shutdown ! interface Ethernet1 ip address 192.168.3.33 255.255.255.224 ! interface Ethernet2 --More-- %OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area mu st be virtual-link but not found from 192.168.2.254, Ethernet3 shutdown ! interface Ethernet3 ip address 192.168.1.1 255.255.255.0 ! interface Ethernet4 no ip address shutdown ! interface Ethernet5 ip address 192.168.3.65 255.255.255.224 ! interface Ethernet6 no ip address shutdown ! interface Ethernet7 no ip address shutdown ! interface Fddi0 no ip address --More-- router ospf 1 network 192.168.3.32 0.0.0.31 area 2 network 192.168.3.64 0.0.0.31 area 2 network 192.168.1.0 0.0.0.255 area 1 area 2 range 192.168.3.0 255.255.255.0 area 1 virtual-link 1.1.1.1 ! logging console notifications ! ! line con 0 line aux 0 transport input all line vty 0 4 login ! end enable password lab ! ! interface Loopback0 ip address 1.1.1.1 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.254 255.255.255.0 no keepalive ! interface Ethernet1 ip address 192.168.2.1 255.255.255.0 ! interface Ethernet2 --More-- router ospf 1 network 192.168.2.0 0.0.0.255 area 0 network 192.168.1.0 0.0.0.255 area 1 area 1 virtual-link 2.2.2.2 Current configuration: ! version 10.2 service tcp-small-servers ! hostname dogbert ! enable password lab ! ! interface Loopback0 ip address 3.3.3.3 255.255.255.0 ! interface Ethernet0 ip address 192.168.2.254 255.255.255.0 ! interface Ethernet1 no ip address shutdown ! interface Fddi0 no ip address no keepalive shutdown ! interface Hssi0 no ip address shutdown ! interface Serial0 no ip address shutdown ! interface Serial1 no ip address shutdown ! router ospf 1 network 192.168.2.0 0.0.0.255 area 0 ! ! ! line con 0 line aux 0 transport input all --More-- [GroupStudy.com removed an attachment of type application/x-mspowerpoint which had a name of logical_diag_v3.ppt] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=674t=674 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: I need Help!!! Kindly help me(OSPF Virtual links) [7:674]
Looks like you have E0 of dogbert (area 1) in the same ethernet broadcast domain as E3 of aspen (Area 0). The only reason you are not seeing a similar message in dogbert is cause your console logging level is differnet in dogbert DaveC Shahid Muhammad Shafi wrote: Hi Guys. I am configuring a virtual link between two OSPF routers but it is not working at all. I am sending u the configuration and diagram here;. Any help and pinters will be appreciated. Regards Shahid = Shahid Muhammad Shafi MSc Telecommunications Candidate University of Colorado Boulder BSEE(GIKI),MCSE+I,CNA,CCNA,CCNP Please help feed hungry people worldwide http://www.hungersite.com/ A small thing each of us can do to help others less fortunate than ourselves __ Do You Yahoo!? Get email at your own domain with Yahoo! Mail. http://personal.mail.yahoo.com/ Current configuration: ! version 10.2 service tcp-small-servers ! hostname catbert ! enable password lab ! ! interface Ethernet0 ip address 192.168.3.126 255.255.255.224 ! interface Ethernet1 ip address 192.168.3.62 255.255.255.224 ! interface Ethernet2 no ip address shutdown ! interface Ethernet3 ip address 192.168.21.120 255.255.255.0 ! interface Ethernet4 no ip address shutdown ! interface Ethernet5 no ip address shutdown ! interface Ethernet6 no ip address shutdown ! interface Ethernet7 no ip address shutdown ! interface Ethernet8 no ip address shutdown ! interface Ethernet9 ip address 192.168.90.1 255.255.255.0 shutdown ! interface Ethernet10 ip address 192.168.100.1 255.255.255.0 ! interface Ethernet11 ip address 192.168.80.1 255.255.255.0 ! interface Fddi0 no ip address no keepalive shutdown ! interface Hssi0 no ip address shutdown ! router ospf 1 network 192.168.3.32 0.0.0.31 area 2 network 192.168.3.96 0.0.0.31 area 2 ! no logging console ! ! line con 0 exec-timeout 0 0 password lab login line aux 0 password lab login transport input all line vty 0 4 password lab login ! end Current configuration: ! version 10.2 ! hostname breckenridge ! enable password lab ! ! interface Ethernet0 ip address 192.168.3.97 255.255.255.224 ! interface Ethernet1 ip address 192.168.3.94 255.255.255.224 ! router ospf 1 network 192.168.3.96 0.0.0.31 area 2 network 192.168.3.64 0.0.0.31 area 2 ! Current configuration: ! version 11.0 service udp-small-servers service tcp-small-servers ! hostname aspen ! enable password lab ! ! interface Loopback0 ip address 2.2.2.2 255.255.255.0 ! interface Ethernet0 no ip address shutdown ! interface Ethernet1 ip address 192.168.3.33 255.255.255.224 ! interface Ethernet2 --More-- %OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area mu st be virtual-link but not found from 192.168.2.254, Ethernet3 shutdown ! interface Ethernet3 ip address 192.168.1.1 255.255.255.0 ! interface Ethernet4 no ip address shutdown ! interface Ethernet5 ip address 192.168.3.65 255.255.255.224 ! interface Ethernet6 no ip address shutdown ! interface Ethernet7 no ip address shutdown ! interface Fddi0 no ip address --More-- router ospf 1 network 192.168.3.32 0.0.0.31 area 2 network 192.168.3.64 0.0.0.31 area 2 network 192.168.1.0 0.0.0.255 area 1 area 2 range 192.168.3.0 255.255.255.0 area 1 virtual-link 1.1.1.1 ! logging console notifications ! ! line con 0 line aux 0 transport input all line vty 0 4 login ! end enable password lab ! ! interface Loopback0 ip address 1.1.1.1 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.254 255.255.255.0 no keepalive ! interface Ethernet1 ip address 192.168.2.1 255.255.255.0 ! interface Ethernet2 --More-- router ospf 1 network 192.168.2.0 0.0.0.255 area 0 network 192.168.1.0 0.0.0.255 area 1 area 1 virtual-link 2.2.2.2 Current configuration: ! version 10.2 service tcp-small-servers ! hostname dogbert ! enable password lab ! ! interface Loopback0 ip address 3.3.3.3 255.255.255.0 ! interface Ethernet0 ip address 192.168.2.254 255.255.255.0 ! interface Ethernet1 no ip address shutdown ! interface Fddi0 no ip address no keepalive shutdown ! interface Hssi0 no ip address shutdown ! interface Serial0 no ip address shutdown ! interface Serial1 no ip address shutdown ! router ospf 1 network 192.168.2.0 0.0.0.255 area 0 ! ! ! line con 0 line aux 0 transport input all --More-- [GroupStudy.com removed an attachment of type application/x-mspowerpoint which had a name of logical_diag_v3.ppt] 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=683t=674 -- FAQ, list archives,
Re: OSPF virtual links
At 03:59 PM 4/7/01 -0400, Fred Danson wrote: Fred I setup Lab #30 just to see if I would experience the same thing, and initially I did, until I rebooted RouterA (your R2503). Somehow rebooting allowed reachability and I was able to ping the 152.1.1.1 address (actaully I used 192.168.104.3). I also noticed the "ip ospf interface-retry 0" on several interfaces in your config, I had them in mine's also. I gotta look that one up but I suspect that it appears in the config because the opposite side of the link hasn't been initialized or configured yet! After I deleted all the "ip ospf interface-retry 0" entries off the interface configs and rebooted all three routers, I still have reachibility to 192.168.104.3 (your 152.1.1.1) and also found that network 192.168.104.0 (your 152.1.0.0) is in the routing table of RouterB (your 2523). I have all the router configs and sh commands as well as the capture of the successful ping, but I'll reserve posting them to save bandwidth until I hear if you rebooted and cleaned up the configs and your problem still exist. Stefan Hey group, I am in the middle of Lab #30 from the CCIE Lab Study Guide which involves OSPF virtual links. Here's my configs: R2503 - backbone router hostname r2503 ! ! ip subnet-zero ! ! ! interface Loopback0 ip address 1.1.1.1 255.255.255.0 no ip directed-broadcast ! interface Ethernet0 no ip address no ip directed-broadcast shutdown ! interface Serial0 ip address 192.1.1.1 255.255.255.0 no ip directed-broadcast ip ospf interface-retry 0 no ip mroute-cache no fair-queue ! interface Serial1 no ip address no ip directed-broadcast shutdown ! interface BRI0 no ip address no ip directed-broadcast shutdown ! router ospf 100 network 192.1.1.1 0.0.0.0 area 0 ! ip classless ! ! ! line con 0 transport input none line aux 0 line vty 0 4 ! end -- R2523- backbone router, link between R2503 R4000 hostname r2523 ! ! ip subnet-zero ! ! ! interface Loopback0 ip address 2.2.2.2 255.255.255.0 no ip directed-broadcast ! interface Serial0 ip address 193.1.1.2 255.255.255.0 no ip directed-broadcast ip ospf interface-retry 0 no ip mroute-cache no fair-queue ! interface Serial1 ip address 192.1.1.2 255.255.255.0 no ip directed-broadcast ip ospf interface-retry 0 clockrate 64000 ! interface Serial2 no ip address no ip directed-broadcast shutdown ! interface Serial3 no ip address no ip directed-broadcast shutdown ! interface Serial4 no ip address no ip directed-broadcast shutdown ! interface Serial5 no ip address no ip directed-broadcast shutdown ! interface Serial6 no ip address no ip directed-broadcast shutdown ! interface Serial7 no ip address no ip directed-broadcast shutdown ! interface Serial8 no ip address no ip directed-broadcast shutdown ! interface Serial9 no ip address no ip directed-broadcast shutdown ! interface TokenRing0 no ip address no ip directed-broadcast shutdown ! interface BRI0 no ip address no ip directed-broadcast shutdown ! router ospf 100 area 1 virtual-link 3.3.3.3 network 192.1.1.2 0.0.0.0 area 0 network 193.1.1.2 0.0.0.0 area 1 ! ip classless ! ! ! line con 0 transport input none line aux 0 line vty 0 4 ! end - R4000, in areas 1 4, has a virtual link through R2523 hostname r4000 ! ! ! ! interface Loopback0 ip address 3.3.3.3 255.255.255.0 ! interface Ethernet0 ip address 152.1.1.1 255.255.255.0 no keepalive media-type 10BaseT ! interface Serial0 ip address 193.1.1.1 255.255.255.0 no ip mroute-cache no fair-queue clockrate 64000 ! interface Serial1 no ip address shutdown ! interface TokenRing0 no ip address shutdown ! router ospf 100 network 152.1.1.1 0.0.0.0 area 4 network 193.1.1.1 0.0.0.0 area 1 area 1 virtual-link 2.2.2.2 ! ip classless ! ! ! line con 0 line aux 0 line vty 0 4 login ! end - the virtual link seems to be working fine. Here's a paste of show ip ospf virtual-link from r2523 r2523#show ip ospf vir Virtual Link OSPF_VL0 to router 3.3.3.3 is up Run as demand circuit DoNotAge LSA allowed. Transit area 1, via interface Serial0, Cost of using 64 Transmit Delay is 1 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:01 Adjacency State FULL (Hello suppressed) Here's a paste of show ip ospf virtual-link from r4000 r4000#show ip ospf vir Virtual Link OSPF_VL0 to router 2.2.2.2 is up Run as demand circuit DoNotAge LSA allowed. Transit area 1, via interface Serial0, Cost of using 64 Transmit Delay is 1 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:03 Adjacency State FULL (Hello suppressed) Here's the problem. I cannot ping r4000's ethernet interface (which is in area 4) from r2503. the network statement for 152.1.1.0/24 is in r2503's route table, but not in r2523's route table. r2503#show ip route Codes: C - c
Re: OSPF virtual links
At 03:59 PM 4/7/01 -0400, Fred Danson wrote: interface Serial0 ip address 192.1.1.1 255.255.255.0 no ip directed-broadcast ip ospf interface-retry 0 see CCO link below no ip mroute-cache no fair-queue http://www.cisco.com/warp/public/104/28.shtml Stefan _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF virtual links
My comments follow below. Please let me know how it worked out. --- OSPF virtual links. Here's my configs: R2503 - backbone router hostname r2503 ! router ospf 100 network 192.1.1.1 0.0.0.0 area 0 -- Please change your config to: router ospf 100 network 192.1.1.0 0.0.0.255 area 0 --- R2523- backbone router, link between R2503 R4000 hostname r2523 router ospf 100 area 1 virtual-link 3.3.3.3 network 192.1.1.2 0.0.0.0 area 0 network 193.1.1.2 0.0.0.0 area 1 - For R2523, please change your config to: router ospf 100 area 1 virtual-link 3.3.3.3 network 192.1.1.0 0.0.0.255 area 0 network 193.1.1.0 0.0.0.255 area 1 --- R4000, in areas 1 4, has a virtual link through R2523 hostname r4000 router ospf 100 network 152.1.1.1 0.0.0.0 area 4 network 193.1.1.1 0.0.0.0 area 1 area 1 virtual-link 2.2.2.2 ! - For R4000, please change your config to: router ospf 100 network 152.1.1.0 0.0.0.255 area 4 network 193.1.1.0 0.0.0.255 area 1 area 1 virtual-link 2.2.2.2 --- Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ Get your FREE download of MSN Explorer at http://explorer.msn.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF virtual links
The changes you listed really won't do anything. As long as the IP address on the interface falls into the network + wildcard mask range used in the network statement, it will work fine. You can check to see if the interface is active in the ospf process using the show ip ospf interface command. From: "Arthur Simplina" [EMAIL PROTECTED] Reply-To: "Arthur Simplina" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: OSPF virtual links Date: Sun, 08 Apr 2001 20:15:15 -0400 My comments follow below. Please let me know how it worked out. ------- OSPF virtual links. Here's my configs: R2503 - backbone router hostname r2503 ! router ospf 100 network 192.1.1.1 0.0.0.0 area 0 -- Please change your config to: router ospf 100 network 192.1.1.0 0.0.0.255 area 0 --- R2523- backbone router, link between R2503 R4000 hostname r2523 router ospf 100 area 1 virtual-link 3.3.3.3 network 192.1.1.2 0.0.0.0 area 0 network 193.1.1.2 0.0.0.0 area 1 - For R2523, please change your config to: router ospf 100 area 1 virtual-link 3.3.3.3 network 192.1.1.0 0.0.0.255 area 0 network 193.1.1.0 0.0.0.255 area 1 --- R4000, in areas 1 4, has a virtual link through R2523 hostname r4000 router ospf 100 network 152.1.1.1 0.0.0.0 area 4 network 193.1.1.1 0.0.0.0 area 1 area 1 virtual-link 2.2.2.2 ! - For R4000, please change your config to: router ospf 100 network 152.1.1.0 0.0.0.255 area 4 network 193.1.1.0 0.0.0.255 area 1 area 1 virtual-link 2.2.2.2 --- Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ Get your FREE download of MSN Explorer at http://explorer.msn.com _ Get your FREE download of MSN Explorer at http://explorer.msn.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF virtual links
Hey group, I am in the middle of Lab #30 from the CCIE Lab Study Guide which involves OSPF virtual links. Here's my configs: R2503 - backbone router hostname r2503 ! ! ip subnet-zero ! ! ! interface Loopback0 ip address 1.1.1.1 255.255.255.0 no ip directed-broadcast ! interface Ethernet0 no ip address no ip directed-broadcast shutdown ! interface Serial0 ip address 192.1.1.1 255.255.255.0 no ip directed-broadcast ip ospf interface-retry 0 no ip mroute-cache no fair-queue ! interface Serial1 no ip address no ip directed-broadcast shutdown ! interface BRI0 no ip address no ip directed-broadcast shutdown ! router ospf 100 network 192.1.1.1 0.0.0.0 area 0 ! ip classless ! ! ! line con 0 transport input none line aux 0 line vty 0 4 ! end -- R2523- backbone router, link between R2503 R4000 hostname r2523 ! ! ip subnet-zero ! ! ! interface Loopback0 ip address 2.2.2.2 255.255.255.0 no ip directed-broadcast ! interface Serial0 ip address 193.1.1.2 255.255.255.0 no ip directed-broadcast ip ospf interface-retry 0 no ip mroute-cache no fair-queue ! interface Serial1 ip address 192.1.1.2 255.255.255.0 no ip directed-broadcast ip ospf interface-retry 0 clockrate 64000 ! interface Serial2 no ip address no ip directed-broadcast shutdown ! interface Serial3 no ip address no ip directed-broadcast shutdown ! interface Serial4 no ip address no ip directed-broadcast shutdown ! interface Serial5 no ip address no ip directed-broadcast shutdown ! interface Serial6 no ip address no ip directed-broadcast shutdown ! interface Serial7 no ip address no ip directed-broadcast shutdown ! interface Serial8 no ip address no ip directed-broadcast shutdown ! interface Serial9 no ip address no ip directed-broadcast shutdown ! interface TokenRing0 no ip address no ip directed-broadcast shutdown ! interface BRI0 no ip address no ip directed-broadcast shutdown ! router ospf 100 area 1 virtual-link 3.3.3.3 network 192.1.1.2 0.0.0.0 area 0 network 193.1.1.2 0.0.0.0 area 1 ! ip classless ! ! ! line con 0 transport input none line aux 0 line vty 0 4 ! end - R4000, in areas 1 4, has a virtual link through R2523 hostname r4000 ! ! ! ! interface Loopback0 ip address 3.3.3.3 255.255.255.0 ! interface Ethernet0 ip address 152.1.1.1 255.255.255.0 no keepalive media-type 10BaseT ! interface Serial0 ip address 193.1.1.1 255.255.255.0 no ip mroute-cache no fair-queue clockrate 64000 ! interface Serial1 no ip address shutdown ! interface TokenRing0 no ip address shutdown ! router ospf 100 network 152.1.1.1 0.0.0.0 area 4 network 193.1.1.1 0.0.0.0 area 1 area 1 virtual-link 2.2.2.2 ! ip classless ! ! ! line con 0 line aux 0 line vty 0 4 login ! end - the virtual link seems to be working fine. Here's a paste of show ip ospf virtual-link from r2523 r2523#show ip ospf vir Virtual Link OSPF_VL0 to router 3.3.3.3 is up Run as demand circuit DoNotAge LSA allowed. Transit area 1, via interface Serial0, Cost of using 64 Transmit Delay is 1 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:01 Adjacency State FULL (Hello suppressed) Here's a paste of show ip ospf virtual-link from r4000 r4000#show ip ospf vir Virtual Link OSPF_VL0 to router 2.2.2.2 is up Run as demand circuit DoNotAge LSA allowed. Transit area 1, via interface Serial0, Cost of using 64 Transmit Delay is 1 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:03 Adjacency State FULL (Hello suppressed) Here's the problem. I cannot ping r4000's ethernet interface (which is in area 4) from r2503. the network statement for 152.1.1.0/24 is in r2503's route table, but not in r2523's route table. r2503#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is not set 1.0.0.0/24 is subnetted, 1 subnets C 1.1.1.0 is directly connected, Loopback0 152.1.0.0/24 is subnetted, 1 subnets O IA152.1.1.0 [110/138] via 192.1.1.2, 00:17:22, Serial0 O IA 193.1.1.0/24 [110/128] via 192.1.1.2, 00:17:22, Serial0 C192.1.1.0/24 is directly connected, Serial0 r2523#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate
Revisted - OSPF Virtual Links and RIDs
Chuck, I finally got a chance to mock this up in the lab and I've got some pretty cool resultsFirst of all when I did this using pretty much the same scenario the virtual link never went down at any time when the connection to r3 from r2 was shutdown. After clearing the routes and ospf redistribution the virtual-link was still up/up. Theory that stood the testI then used a external routing info.(rip) to advertise routes to the loopback identified with the virtual-link command. With a direct path/route between both loopbacks I then shut down the physical link between R1 and R2. As expected, the virtual-link stayed down and never came back up. In Doyle's book (Routing TCP/IP) he states that the virtual-link must be configured between two ABR's and the area it transits must having full routing info. I take the meaning of this as having a full map of the network. There is also a mention of using a non-backbone area, which I also take to mean - "An OSPF Area" in which case any external routing info used to obtain a path to the loopback would prove useless if not part of an OSPF area that is either directly connected to area or is connected by the same process a virtual-link Just some observations.. Any thoughts...! This is some really cool stuff. Nigel. - Original Message - From: Chuck Larrieu [EMAIL PROTECTED] To: CCIE_Lab Groupstudy List [EMAIL PROTECTED] Sent: Sunday, December 24, 2000 1:12 PM Subject: OSPF Virtual Links and RIDs Just got through with one of the multiprotocol redistribution practice labs ( Mentor Labs 4141 ) Got a question regarding virtual links and loopback RIDs. In the realm of OSPF, when direct ( meaning through the OSPF process ) access to a particular router is lost, does that mean that any virtual link associated with that router is lost? Well, yes, I know, and duh! But my question has to do with the placement of the RID into the routing process. The deal is that there is an alternative link to the OSPF area 0. However it is through a different routing protocol. All routes are redistributed through that protocol, and when the direct i.e. OSPF link between the two endpoints of the virtual link are severed, even though the route to the RID is seen via the redistribution process, the virtual link apparently does not come back up. This leads back to the question of the value of loopback addresses as a cure all for routing process interruptions. In the scenario I ran, there was a classic virtual link. R1-R2---R3 connected via serial links Area2area1.area0 All routers have loopbacks, which under the rules of the game have become the RID's There is also an external routing domain connecting R1 and R3 via the ethernet ports. Redistribution is established, and works just fine. When I severed the serial link between R2 and R3, the virtual link goes down, and does not re-establish itself, even though the RID is being advertised as a route into the exterior domain, and remains in the routing tables of all routers as external routes. I kinda expected this behaviour, but it still raises the question of the supposed benefit of loopbacks as an interface that is "always up" and therefore advantageous to use. One of those "pitfalls" someone was asking about a couple of weeks back, I suppose. Chuck -- I am Locutus, a CCIE Lab Proctor. Xx_Brain_dumps_xX are futile. Your life as it has been is over ( if you hope to pass ) From this time forward, you will study US! ( apologies to the folks at Star Trek TNG ) ___ To unsubscribe from the CCIELAB list, send a message to [EMAIL PROTECTED] with the body containing: unsubscribe ccielab _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
