Re: OSPF for ISPs [7:54540]
At 03:07 PM 9/30/2002 +, Russell Heilling wrote: Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Easiest way to do this without running OSPF on the CPE is to put a static route on the router at your end of the link, and redistribute the static route into OSPF. I like this, but put the static in BGP with some neato communities on it. How are you getting the /30 into OSPF at the moment? If you are using a network statement make sure that you have set the customer interface as passive - the last thing you want is a customer tinkering with the router and injecting bad routes into your network. Alternatively you could redistribute connected routes into OSPF, removing the need for the network statement. -- Russell Heilling http://www.ccie.org.uk/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54872t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF for ISPs [7:54540]
At 04:05 PM 9/30/2002 +, Chris Headings wrote: Great... So it looks like I would then use the redistribute static subnets as well as the redistribute connected subnets command within the OSPF process to make sure ALL ospf enabled routers would know how to reach that specifc, statically routed/connected, destination? This would work, but if you are really designing an ISP, don't clutter up your IGP topology with a bunch of type 5's that are challenging to effectively constrain. Put these customer prefixes in BGP and put together a nice community based routing policy to control your BGP prefixes. Chris Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54873t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF for ISPs [7:54540]
At 07:12 PM 9/30/2002 +, MADMAN wrote: Interesting. I don't work for an ISP bt have worked with many and I have only ran into one that ran an IGP with it's customers and I was suprised. My ancedotal evidence suggests that the vast majority either run BGP or statics to announce customer networks. I know there are plenty of ISP engineers out there and can confirm/rip my conjecture ;) Dave Best practises would dictate the use of static or a distance vector variant IGP for customer connections. The lack of import filtering capability in Link State protocols presents a very dangerous situation for the ISP. In general, ISP's are very paranoid about customers (and peers/providers alike) and take all means necessary to protect themselves from misbehaving external peers (IP peers in this general case) BGP naturally provides the most policy rich tool set for those applications where static routing will not suffice. I find RIP to be a comfortable variant for those multihomed customers who simply will not turn up BGP, though I'd still prefer to have the BGP discussion one last time with them prior to doing using it. Of course, linking one's main IGP to a customers is a really silly idea which I think everyone grasps ;) Mike Bernico wrote: I'm not sure I'm in complete agreement. The network I work for has several distribution routers that contain around 1000 T1 speed customers. If we were to static route each of their networks it would add about 1000 to 1500 lines of router configuration to the router. That would definately add to our maintenance and provisioning work and make troubleshooting harder on our techs. While I agree statics are probably the most stable way, I'm not sure it's necessarily the best way to aggrigate high volumes of customers. We currently use EIGRP at the edge with the stub command, OSPF or IS-IS would work just as well. Regardless, we would never let our IGP, that extends to the CE router, touch their IGP. About 98% of our customers are not BGP customers though. YMMV Mike --- Mike Bernico [EMAIL PROTECTED] Illinois Century Network http://www.illinois.net (217) 557-6555 -Original Message- From: Howard C. Berkowitz [mailto:[EMAIL PROTECTED]] Sent: Monday, September 30, 2002 11:37 AM To: [EMAIL PROTECTED] Subject: Re: OSPF for ISPs [7:54540] At 2:58 PM + 9/30/02, Don wrote: Rather than run OSPF to customers, it is generally much better to have them use a default route to the ISP and for the ISP to run static routes to the customer. OSPF to the customer is a huge land mine for the ISP and should be avoided in almost every case. Don I agree completely with Don that an ISP _never_ should link its IGP to that of the customer. Don't fall into the trap of assuming that BGP needs a full routing table or will consume excessive resources. I remain confused why a default route wouldn't serve, unless there are multiple connections between the ISP and customer. By send the block to the customer, do you mean the block is in the customer's space? You could certainly use a second static route, which can be generated automatically as part of your address assignment (see my NANOG presentation, http://www.nanog.org/mtg-9811/ppt/berk/index.htm). If that's not appropriate, have the customer announce his two blocks to you with BGP and receive default from your BGP. Chris Headings wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Good morning all. I was wondering if someone could lend me a little help about engineering OSPF in the backbone for an ISP network. I just had a couple of questions and hopefully someone can give me some guidance.or even some CCO links with some specific examples or better yet any material anywhere. Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Thanks as always. Chris -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 You don't make the poor richer by making the rich poorer. --Winston Churchill Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54877t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report mi
RE: OSPF for ISPs [7:54540]
What about using default routes at the customer sites? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Peter van Oene Sent: Friday, October 04, 2002 5:17 AM To: [EMAIL PROTECTED] Subject: Re: OSPF for ISPs [7:54540] At 07:12 PM 9/30/2002 +, MADMAN wrote: Interesting. I don't work for an ISP bt have worked with many and I have only ran into one that ran an IGP with it's customers and I was suprised. My ancedotal evidence suggests that the vast majority either run BGP or statics to announce customer networks. I know there are plenty of ISP engineers out there and can confirm/rip my conjecture ;) Dave Best practises would dictate the use of static or a distance vector variant IGP for customer connections. The lack of import filtering capability in Link State protocols presents a very dangerous situation for the ISP. In general, ISP's are very paranoid about customers (and peers/providers alike) and take all means necessary to protect themselves from misbehaving external peers (IP peers in this general case) BGP naturally provides the most policy rich tool set for those applications where static routing will not suffice. I find RIP to be a comfortable variant for those multihomed customers who simply will not turn up BGP, though I'd still prefer to have the BGP discussion one last time with them prior to doing using it. Of course, linking one's main IGP to a customers is a really silly idea which I think everyone grasps ;) Mike Bernico wrote: I'm not sure I'm in complete agreement. The network I work for has several distribution routers that contain around 1000 T1 speed customers. If we were to static route each of their networks it would add about 1000 to 1500 lines of router configuration to the router. That would definately add to our maintenance and provisioning work and make troubleshooting harder on our techs. While I agree statics are probably the most stable way, I'm not sure it's necessarily the best way to aggrigate high volumes of customers. We currently use EIGRP at the edge with the stub command, OSPF or IS-IS would work just as well. Regardless, we would never let our IGP, that extends to the CE router, touch their IGP. About 98% of our customers are not BGP customers though. YMMV Mike --- Mike Bernico [EMAIL PROTECTED] Illinois Century Network http://www.illinois.net (217) 557-6555 -Original Message- From: Howard C. Berkowitz [mailto:[EMAIL PROTECTED]] Sent: Monday, September 30, 2002 11:37 AM To: [EMAIL PROTECTED] Subject: Re: OSPF for ISPs [7:54540] At 2:58 PM + 9/30/02, Don wrote: Rather than run OSPF to customers, it is generally much better to have them use a default route to the ISP and for the ISP to run static routes to the customer. OSPF to the customer is a huge land mine for the ISP and should be avoided in almost every case. Don I agree completely with Don that an ISP _never_ should link its IGP to that of the customer. Don't fall into the trap of assuming that BGP needs a full routing table or will consume excessive resources. I remain confused why a default route wouldn't serve, unless there are multiple connections between the ISP and customer. By send the block to the customer, do you mean the block is in the customer's space? You could certainly use a second static route, which can be generated automatically as part of your address assignment (see my NANOG presentation, http://www.nanog.org/mtg-9811/ppt/berk/index.htm). If that's not appropriate, have the customer announce his two blocks to you with BGP and receive default from your BGP. Chris Headings wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Good morning all. I was wondering if someone could lend me a little help about engineering OSPF in the backbone for an ISP network. I just had a couple of questions and hopefully someone can give me some guidance.or even some CCO links with some specific examples or better yet any material anywhere. Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Thanks as always. Chris -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 You don't make the poo
RE: OSPF for ISPs [7:54540]
Hey Daren, For single homed customers, that makes a lot of sense. I suppose I was speaking more to the situations where a customer my want to dynamically advertise reachability to their provider(s) At 04:32 PM 10/4/2002 +, Daren Presbitero wrote: What about using default routes at the customer sites? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Peter van Oene Sent: Friday, October 04, 2002 5:17 AM To: [EMAIL PROTECTED] Subject: Re: OSPF for ISPs [7:54540] At 07:12 PM 9/30/2002 +, MADMAN wrote: Interesting. I don't work for an ISP bt have worked with many and I have only ran into one that ran an IGP with it's customers and I was suprised. My ancedotal evidence suggests that the vast majority either run BGP or statics to announce customer networks. I know there are plenty of ISP engineers out there and can confirm/rip my conjecture ;) Dave Best practises would dictate the use of static or a distance vector variant IGP for customer connections. The lack of import filtering capability in Link State protocols presents a very dangerous situation for the ISP. In general, ISP's are very paranoid about customers (and peers/providers alike) and take all means necessary to protect themselves from misbehaving external peers (IP peers in this general case) BGP naturally provides the most policy rich tool set for those applications where static routing will not suffice. I find RIP to be a comfortable variant for those multihomed customers who simply will not turn up BGP, though I'd still prefer to have the BGP discussion one last time with them prior to doing using it. Of course, linking one's main IGP to a customers is a really silly idea which I think everyone grasps ;) Mike Bernico wrote: I'm not sure I'm in complete agreement. The network I work for has several distribution routers that contain around 1000 T1 speed customers. If we were to static route each of their networks it would add about 1000 to 1500 lines of router configuration to the router. That would definately add to our maintenance and provisioning work and make troubleshooting harder on our techs. While I agree statics are probably the most stable way, I'm not sure it's necessarily the best way to aggrigate high volumes of customers. We currently use EIGRP at the edge with the stub command, OSPF or IS-IS would work just as well. Regardless, we would never let our IGP, that extends to the CE router, touch their IGP. About 98% of our customers are not BGP customers though. YMMV Mike --- Mike Bernico [EMAIL PROTECTED] Illinois Century Network http://www.illinois.net (217) 557-6555 -Original Message- From: Howard C. Berkowitz [mailto:[EMAIL PROTECTED]] Sent: Monday, September 30, 2002 11:37 AM To: [EMAIL PROTECTED] Subject: Re: OSPF for ISPs [7:54540] At 2:58 PM + 9/30/02, Don wrote: Rather than run OSPF to customers, it is generally much better to have them use a default route to the ISP and for the ISP to run static routes to the customer. OSPF to the customer is a huge land mine for the ISP and should be avoided in almost every case. Don I agree completely with Don that an ISP _never_ should link its IGP to that of the customer. Don't fall into the trap of assuming that BGP needs a full routing table or will consume excessive resources. I remain confused why a default route wouldn't serve, unless there are multiple connections between the ISP and customer. By send the block to the customer, do you mean the block is in the customer's space? You could certainly use a second static route, which can be generated automatically as part of your address assignment (see my NANOG presentation, http://www.nanog.org/mtg-9811/ppt/berk/index.htm). If that's not appropriate, have the customer announce his two blocks to you with BGP and receive default from your BGP. Chris Headings wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Good morning all. I was wondering if someone could lend me a little help about engineering OSPF in the backbone for an ISP network. I just had a couple of questions and hopefully someone can give me some guidance.or even some CCO links with some specific examples or better yet any material anywhere. Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the
Re: OSPF for ISPs [7:54540]
I think it should be pointed out here that the land mine isn't even linking the customers IGP to the ISP's IGP. The land mine is linking the IGP's of the customers to each other. Consider having 1000 customers, all advertising their nets to this IGP, then consider what happens when one of them decides to makes a net entry that is flat out wrong. For instance, customer A decides he now wants to add network B and starts advertising it in the IGP to the ISP. Customer B and the ISP suddenly have major problems. The only way to prevent this to is install route filters for all 1000 customers. And fixing it after it happens is a major nightmare. And do you really think every one of those 1000 customers will advertise their networks correctly? Personally, I find it much easier and safer to do 1000 static routes. The solution below only works if the ISP has sole control of each of the 1000 customers edge routers. And again, 1000 static routes is more reasonable than adding the burden of managing 1000+ more routers. Imagine the password nightmare (or did you really expect to put the same password on the routers of two different customers?). So now we add a RADIUS server. Don Mike Bernico wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm not sure I'm in complete agreement. The network I work for has several distribution routers that contain around 1000 T1 speed customers. If we were to static route each of their networks it would add about 1000 to 1500 lines of router configuration to the router. That would definately add to our maintenance and provisioning work and make troubleshooting harder on our techs. While I agree statics are probably the most stable way, I'm not sure it's necessarily the best way to aggrigate high volumes of customers. We currently use EIGRP at the edge with the stub command, OSPF or IS-IS would work just as well. Regardless, we would never let our IGP, that extends to the CE router, touch their IGP. About 98% of our customers are not BGP customers though. YMMV Mike --- Mike Bernico [EMAIL PROTECTED] Illinois Century Network http://www.illinois.net (217) 557-6555 -Original Message- From: Howard C. Berkowitz [mailto:[EMAIL PROTECTED]] Sent: Monday, September 30, 2002 11:37 AM To: [EMAIL PROTECTED] Subject: Re: OSPF for ISPs [7:54540] At 2:58 PM + 9/30/02, Don wrote: Rather than run OSPF to customers, it is generally much better to have them use a default route to the ISP and for the ISP to run static routes to the customer. OSPF to the customer is a huge land mine for the ISP and should be avoided in almost every case. Don I agree completely with Don that an ISP _never_ should link its IGP to that of the customer. Don't fall into the trap of assuming that BGP needs a full routing table or will consume excessive resources. I remain confused why a default route wouldn't serve, unless there are multiple connections between the ISP and customer. By send the block to the customer, do you mean the block is in the customer's space? You could certainly use a second static route, which can be generated automatically as part of your address assignment (see my NANOG presentation, http://www.nanog.org/mtg-9811/ppt/berk/index.htm). If that's not appropriate, have the customer announce his two blocks to you with BGP and receive default from your BGP. Chris Headings wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Good morning all. I was wondering if someone could lend me a little help about engineering OSPF in the backbone for an ISP network. I just had a couple of questions and hopefully someone can give me some guidance.or even some CCO links with some specific examples or better yet any material anywhere. Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Thanks as always. Chris Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54664t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF for ISPs [7:54540]
I work for an ISP and we simply run a static route of those IPs for the customer and just redist. static routes via EIGRP. Updates are usually not affected much, either, as we have made sure that any subnets that we route to a customer already exist on that router, therefore router summarization takes over and there's very little increase in the broadcast traffic. We also try to make sure that no customers are more than one hope away from our border routers. For whatever good this does you. :) Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54667t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF for ISPs [7:54540]
John, John Hutchison wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I work for an ISP and we simply run a static route of those IPs for the customer and just redist. static routes via EIGRP. I guess you mean redistribute the customer static routes into BGP? Updates are usually not affected much, either, as we have made sure that any subnets that we route to a customer already exist on that router I hope you filter the inbond traffic too, I think this is actually more useful. None exist subnets will be dropped at the customer end anyway, they are paying for their inboud :) .02 --kent therefore router summarization takes over and there's very little increase in the broadcast traffic. We also try to make sure that no customers are more than one hope away from our border routers. For whatever good this does you. :) Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54669t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF for ISPs [7:54540]
At 8:57 PM + 10/1/02, Don wrote: I think it should be pointed out here that the land mine isn't even linking the customers IGP to the ISP's IGP. The land mine is linking the IGP's of the customers to each other. Consider having 1000 customers, all advertising their nets to this IGP, then consider what happens when one of them decides to makes a net entry that is flat out wrong. For instance, customer A decides he now wants to add network B and starts advertising it in the IGP to the ISP. Customer B and the ISP suddenly have major problems. The only way to prevent this to is install route filters for all 1000 customers. And fixing it after it happens is a major nightmare. And do you really think every one of those 1000 customers will advertise their networks correctly? Personally, I find it much easier and safer to do 1000 static routes. The solution below only works if the ISP has sole control of each of the 1000 customers edge routers. And again, 1000 static routes is more reasonable than adding the burden of managing 1000+ more routers. Imagine the password nightmare (or did you really expect to put the same password on the routers of two different customers?). So now we add a RADIUS server. Don Excellent points. I think many people assume static routes are unmanageable because they think they have to configure them manually. Not so. I don't know of an ISP that doesn't use some automated tool, even a spreadsheet, to manage address space it assigns to customers. These things can print reports, which can become files! Assume all your customers get /24 blocks in 10.1.0.0, and you assign a /30 from 10.0.0.0/23 to their link to you. Example: LAN WAN 10.1.0.0/24 10.0.0.0/30 10.1.1.0/24 10.0.0.4/30 10.1.2.0/24 10.0.0.8/30 Create a couple of conventions: -- the LAN router interface is the highest address in the subnet, in this case .254. -- the customer end of the WAN link is .1 -- the ISP end of the WAN link is .2 Now, as you check off the address assignment, generate the statement: ip route 255.255.255.0 and put it in a configuration library for the distribution router You can get this information into the distribution router without rebooting using a telnet script or various copy/merge operations into RAM or NVRAM. In like manner, you can generate the default route for the remote router, and DNS RR records for everything. Mike Bernico wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm not sure I'm in complete agreement. The network I work for has several distribution routers that contain around 1000 T1 speed customers. If we were to static route each of their networks it would add about 1000 to 1500 lines of router configuration to the router. That would definately add to our maintenance and provisioning work and make troubleshooting harder on our techs. While I agree statics are probably the most stable way, I'm not sure it's necessarily the best way to aggrigate high volumes of customers. We currently use EIGRP at the edge with the stub command, OSPF or IS-IS would work just as well. Regardless, we would never let our IGP, that extends to the CE router, touch their IGP. About 98% of our customers are not BGP customers though. YMMV Mike --- Mike Bernico [EMAIL PROTECTED] Illinois Century Network http://www.illinois.net (217) 557-6555 -Original Message- From: Howard C. Berkowitz [mailto:[EMAIL PROTECTED]] Sent: Monday, September 30, 2002 11:37 AM To: [EMAIL PROTECTED] Subject: Re: OSPF for ISPs [7:54540] At 2:58 PM + 9/30/02, Don wrote: Rather than run OSPF to customers, it is generally much better to have them use a default route to the ISP and for the ISP to run static routes to the customer. OSPF to the customer is a huge land mine for the ISP and should be avoided in almost every case. Don I agree completely with Don that an ISP _never_ should link its IGP to that of the customer. Don't fall into the trap of assuming that BGP needs a full routing table or will consume excessive resources. I remain confused why a default route wouldn't serve, unless there are multiple connections between the ISP and customer. By send the block to the customer, do you mean the block is in the customer's space? You could certainly use a second static route, which can be generated automatically as part of your address assignment (see my NANOG presentation, http://www.nanog.org/mtg-9811/ppt/berk/index.htm). If that's not appropriate, have the customer announce his two blocks to you with BGP and receive default from your BGP. Chris Headings wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Good morning all. I was wondering if someone could lend me a little
OSPF for ISPs [7:54540]
Good morning all. I was wondering if someone could lend me a little help about engineering OSPF in the backbone for an ISP network. I just had a couple of questions and hopefully someone can give me some guidance or even some CCO links with some specific examples or better yet any material anywhere Say, for example, that a customer has a small block of IPs and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Thanks as always Chris Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54540t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF for ISPs [7:54540]
Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Easiest way to do this without running OSPF on the CPE is to put a static route on the router at your end of the link, and redistribute the static route into OSPF. How are you getting the /30 into OSPF at the moment? If you are using a network statement make sure that you have set the customer interface as passive - the last thing you want is a customer tinkering with the router and injecting bad routes into your network. Alternatively you could redistribute connected routes into OSPF, removing the need for the network statement. -- Russell Heilling http://www.ccie.org.uk/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54543t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF for ISPs [7:54540]
Rather than run OSPF to customers, it is generally much better to have them use a default route to the ISP and for the ISP to run static routes to the customer. OSPF to the customer is a huge land mine for the ISP and should be avoided in almost every case. Don Chris Headings wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Good morning all. I was wondering if someone could lend me a little help about engineering OSPF in the backbone for an ISP network. I just had a couple of questions and hopefully someone can give me some guidance.or even some CCO links with some specific examples or better yet any material anywhere. Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Thanks as always. Chris Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54541t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF for ISPs [7:54540]
Great... So it looks like I would then use the redistribute static subnets as well as the redistribute connected subnets command within the OSPF process to make sure ALL ospf enabled routers would know how to reach that specifc, statically routed/connected, destination? Chris Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54548t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF for ISPs [7:54540]
At 2:58 PM + 9/30/02, Don wrote: Rather than run OSPF to customers, it is generally much better to have them use a default route to the ISP and for the ISP to run static routes to the customer. OSPF to the customer is a huge land mine for the ISP and should be avoided in almost every case. Don I agree completely with Don that an ISP _never_ should link its IGP to that of the customer. Don't fall into the trap of assuming that BGP needs a full routing table or will consume excessive resources. I remain confused why a default route wouldn't serve, unless there are multiple connections between the ISP and customer. By send the block to the customer, do you mean the block is in the customer's space? You could certainly use a second static route, which can be generated automatically as part of your address assignment (see my NANOG presentation, http://www.nanog.org/mtg-9811/ppt/berk/index.htm). If that's not appropriate, have the customer announce his two blocks to you with BGP and receive default from your BGP. Chris Headings wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Good morning all. I was wondering if someone could lend me a little help about engineering OSPF in the backbone for an ISP network. I just had a couple of questions and hopefully someone can give me some guidance.or even some CCO links with some specific examples or better yet any material anywhere. Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Thanks as always. Chris Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54550t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF for ISPs [7:54540]
I'm not sure I'm in complete agreement. The network I work for has several distribution routers that contain around 1000 T1 speed customers. If we were to static route each of their networks it would add about 1000 to 1500 lines of router configuration to the router. That would definately add to our maintenance and provisioning work and make troubleshooting harder on our techs. While I agree statics are probably the most stable way, I'm not sure it's necessarily the best way to aggrigate high volumes of customers. We currently use EIGRP at the edge with the stub command, OSPF or IS-IS would work just as well. Regardless, we would never let our IGP, that extends to the CE router, touch their IGP. About 98% of our customers are not BGP customers though. YMMV Mike --- Mike Bernico [EMAIL PROTECTED] Illinois Century Network http://www.illinois.net (217) 557-6555 -Original Message- From: Howard C. Berkowitz [mailto:[EMAIL PROTECTED]] Sent: Monday, September 30, 2002 11:37 AM To: [EMAIL PROTECTED] Subject: Re: OSPF for ISPs [7:54540] At 2:58 PM + 9/30/02, Don wrote: Rather than run OSPF to customers, it is generally much better to have them use a default route to the ISP and for the ISP to run static routes to the customer. OSPF to the customer is a huge land mine for the ISP and should be avoided in almost every case. Don I agree completely with Don that an ISP _never_ should link its IGP to that of the customer. Don't fall into the trap of assuming that BGP needs a full routing table or will consume excessive resources. I remain confused why a default route wouldn't serve, unless there are multiple connections between the ISP and customer. By send the block to the customer, do you mean the block is in the customer's space? You could certainly use a second static route, which can be generated automatically as part of your address assignment (see my NANOG presentation, http://www.nanog.org/mtg-9811/ppt/berk/index.htm). If that's not appropriate, have the customer announce his two blocks to you with BGP and receive default from your BGP. Chris Headings wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Good morning all. I was wondering if someone could lend me a little help about engineering OSPF in the backbone for an ISP network. I just had a couple of questions and hopefully someone can give me some guidance.or even some CCO links with some specific examples or better yet any material anywhere. Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Thanks as always. Chris Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54556t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF for ISPs [7:54540]
Interesting. I don't work for an ISP bt have worked with many and I have only ran into one that ran an IGP with it's customers and I was suprised. My ancedotal evidence suggests that the vast majority either run BGP or statics to announce customer networks. I know there are plenty of ISP engineers out there and can confirm/rip my conjecture ;) Dave Mike Bernico wrote: I'm not sure I'm in complete agreement. The network I work for has several distribution routers that contain around 1000 T1 speed customers. If we were to static route each of their networks it would add about 1000 to 1500 lines of router configuration to the router. That would definately add to our maintenance and provisioning work and make troubleshooting harder on our techs. While I agree statics are probably the most stable way, I'm not sure it's necessarily the best way to aggrigate high volumes of customers. We currently use EIGRP at the edge with the stub command, OSPF or IS-IS would work just as well. Regardless, we would never let our IGP, that extends to the CE router, touch their IGP. About 98% of our customers are not BGP customers though. YMMV Mike --- Mike Bernico [EMAIL PROTECTED] Illinois Century Network http://www.illinois.net (217) 557-6555 -Original Message- From: Howard C. Berkowitz [mailto:[EMAIL PROTECTED]] Sent: Monday, September 30, 2002 11:37 AM To: [EMAIL PROTECTED] Subject: Re: OSPF for ISPs [7:54540] At 2:58 PM + 9/30/02, Don wrote: Rather than run OSPF to customers, it is generally much better to have them use a default route to the ISP and for the ISP to run static routes to the customer. OSPF to the customer is a huge land mine for the ISP and should be avoided in almost every case. Don I agree completely with Don that an ISP _never_ should link its IGP to that of the customer. Don't fall into the trap of assuming that BGP needs a full routing table or will consume excessive resources. I remain confused why a default route wouldn't serve, unless there are multiple connections between the ISP and customer. By send the block to the customer, do you mean the block is in the customer's space? You could certainly use a second static route, which can be generated automatically as part of your address assignment (see my NANOG presentation, http://www.nanog.org/mtg-9811/ppt/berk/index.htm). If that's not appropriate, have the customer announce his two blocks to you with BGP and receive default from your BGP. Chris Headings wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Good morning all. I was wondering if someone could lend me a little help about engineering OSPF in the backbone for an ISP network. I just had a couple of questions and hopefully someone can give me some guidance.or even some CCO links with some specific examples or better yet any material anywhere. Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Thanks as always. Chris -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 You don't make the poor richer by making the rich poorer. --Winston Churchill Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54559t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF for ISPs [7:54540]
Mike Bernico wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm not sure I'm in complete agreement. The network I work for has several distribution routers that contain around 1000 T1 speed customers. If we were to static route each of their networks it would add about 1000 to 1500 lines of router configuration to the router. That would definately add to our maintenance and provisioning work and make troubleshooting harder on our techs. While I agree statics are probably the most stable way, I'm not sure it's necessarily the best way to aggrigate high volumes of customers. We currently use EIGRP at the edge with the stub command, OSPF or IS-IS would work just as well. Regardless, we would never let our IGP, that extends to the CE router, touch their IGP. About 98% of our customers are not BGP customers though. Well, what you have just described isn't very different from what HB and Madman have described. It's just that in your case, the CE router is effectively part of your ISP. And since you said yourself that you would never link your ISP's IGP with a customer's IGP, that's pretty much exactly what HB has said, it's just that the 'demarc' is in a different place. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54563t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF for ISPs [7:54540]
Well I work for an ISP, and I would have to say that it depends. For most customers (i.e. unmanaged) they just get a static route on the edge router which get redistributed in OSPF. If the customer happends to be in our managed program, we would then run OSPF to them. But if they happen to be in the MPLS-VPN catagory, well then we establish a BGP connection to them, and for larger customers we actually run a standard E-BGP session with them as they are mulithomed with another provider. So no one method will fit all of our customers. I agree those 1000 extra lines in the configs are a bit troublesome until you figure out how to parse the config efficently. (i.e. show run | beg show run |inc ) This really helps when searching for something. Erich -Original Message- From: MADMAN [mailto:[EMAIL PROTECTED]] Sent: Monday, September 30, 2002 12:13 PM To: [EMAIL PROTECTED] Subject: Re: OSPF for ISPs [7:54540] Interesting. I don't work for an ISP bt have worked with many and I have only ran into one that ran an IGP with it's customers and I was suprised. My ancedotal evidence suggests that the vast majority either run BGP or statics to announce customer networks. I know there are plenty of ISP engineers out there and can confirm/rip my conjecture ;) Dave Mike Bernico wrote: I'm not sure I'm in complete agreement. The network I work for has several distribution routers that contain around 1000 T1 speed customers. If we were to static route each of their networks it would add about 1000 to 1500 lines of router configuration to the router. That would definately add to our maintenance and provisioning work and make troubleshooting harder on our techs. While I agree statics are probably the most stable way, I'm not sure it's necessarily the best way to aggrigate high volumes of customers. We currently use EIGRP at the edge with the stub command, OSPF or IS-IS would work just as well. Regardless, we would never let our IGP, that extends to the CE router, touch their IGP. About 98% of our customers are not BGP customers though. YMMV Mike --- Mike Bernico [EMAIL PROTECTED] Illinois Century Network http://www.illinois.net (217) 557-6555 -Original Message- From: Howard C. Berkowitz [mailto:[EMAIL PROTECTED]] Sent: Monday, September 30, 2002 11:37 AM To: [EMAIL PROTECTED] Subject: Re: OSPF for ISPs [7:54540] At 2:58 PM + 9/30/02, Don wrote: Rather than run OSPF to customers, it is generally much better to have them use a default route to the ISP and for the ISP to run static routes to the customer. OSPF to the customer is a huge land mine for the ISP and should be avoided in almost every case. Don I agree completely with Don that an ISP _never_ should link its IGP to that of the customer. Don't fall into the trap of assuming that BGP needs a full routing table or will consume excessive resources. I remain confused why a default route wouldn't serve, unless there are multiple connections between the ISP and customer. By send the block to the customer, do you mean the block is in the customer's space? You could certainly use a second static route, which can be generated automatically as part of your address assignment (see my NANOG presentation, http://www.nanog.org/mtg-9811/ppt/berk/index.htm). If that's not appropriate, have the customer announce his two blocks to you with BGP and receive default from your BGP. Chris Headings wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Good morning all. I was wondering if someone could lend me a little help about engineering OSPF in the backbone for an ISP network. I just had a couple of questions and hopefully someone can give me some guidance.or even some CCO links with some specific examples or better yet any material anywhere. Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Thanks as always. Chris -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 You don't make the poor richer by making the rich poorer. --Winston Churchill Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54564t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations t
Re: OSPF for ISPs [7:54540]
Howard, Is there an audio tape that goes with the slides. If so, I'd being willing to pay so I could show this presentation to my CCNP students, including the shameless plug. BTW, liked your concise explanation of CIDR vs VLSM. Prof. Tom Lisa, CCAI Community College of Southern Nevada Cisco ATC/Regional Networking Academy Howard C. Berkowitz wrote: At 2:58 PM + 9/30/02, Don wrote: Rather than run OSPF to customers, it is generally much better to have them use a default route to the ISP and for the ISP to run static routes to the customer. OSPF to the customer is a huge land mine for the ISP and should be avoided in almost every case. Don I agree completely with Don that an ISP _never_ should link its IGP to that of the customer. Don't fall into the trap of assuming that BGP needs a full routing table or will consume excessive resources. I remain confused why a default route wouldn't serve, unless there are multiple connections between the ISP and customer. By send the block to the customer, do you mean the block is in the customer's space? You could certainly use a second static route, which can be generated automatically as part of your address assignment (see my NANOG presentation, http://www.nanog.org/mtg-9811/ppt/berk/index.htm). If that's not appropriate, have the customer announce his two blocks to you with BGP and receive default from your BGP. Chris Headings wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Good morning all. I was wondering if someone could lend me a little help about engineering OSPF in the backbone for an ISP network. I just had a couple of questions and hopefully someone can give me some guidance.or even some CCO links with some specific examples or better yet any material anywhere. Say, for example, that a customer has a small block of IP's and a distribution router knows where that block is, via a connected route, like a /30 on a serial link. But later down the line the customer requests an additional block of 64 IP addresses, what is the best way to send this block to the customer? Do I need to run OSPF on the customer equipment? If the customer router is not running OSPF, how do the routers know how to get to this destination? I assume via static routing??? Thanks as always. Chris [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54565t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF for ISPs [7:54540]
Howard, Is there an audio tape that goes with the slides. If so, I'd being willing to pay so I could show this presentation to my CCNP students, including the shameless plug. BTW, liked your concise explanation of CIDR vs VLSM. Prof. Tom Lisa, CCAI Community College of Southern Nevada Cisco ATC/Regional Networking Academy Tom, I don't think anyone recorded it -- at some point, NANOG started doing RealVideo. Here's a couple that touch on this subject, and do have sound. Please ignore anything I say about RFC2270--I had a complete brain burp on it. http://www.nanog.org/mtg-0102/exterior.html Exterior Routing 201 http://www.nanog.org/mtg-0102/cust.html Customer Satisfaction 201 this has some stuff on address management, including dynamic generation of static routes. I thought this OSPF tutorial might, but it's PP and HTML only: http://www.nanog.org/mtg-9910/ospf.html This is an updated version of one I did in 1998. Another set of presentations, on which I teamed with Richard Jimmerson of ARIN, also is slides only. Richard talked about the procedures of obtaining address space and I talked about managing it. It used to be on the ARIN.net site, but I can't find it. I'll put it up on the Gett site shortly. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54580t=54540 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
