BGP routing at 2 locations with a link between them

[garycarr]

Hello all. I am trying to reconfigure my network and wanted to be sure what I want to do is possible and maybe find a configuration example. I have 2 POPS with each having a Internet DS3 onsite as well as a DS3 connecting them together. I want to send the local lan traffic on each network destined for the Internet out the Internet DS3 unless one of the Internet DS3s go down, then redirect all the traffic thru the private DS3 and out the Internet DS3. I would like to keep all traffic bound for our networks to stay on our network. I have 1 AS number and around 19 class C adress blocks in /23 and /24 allocations.

Here is what I have

Location A:
Internet DS3: ATM6/0/0
Private DS3: S4/1/0

Location B:
Internet DS3: S6/0
Private DS3: S5/0


Is this possible and can anyone point me to a sample config?

Many thanks in advance!

Gary

 

[jneiberger]

This is pretty simple, and you have a couple of options:

1. Make the sites iBGP peers so that they share BGP information

2. Use a floating static default route at Site A pointing to Site B and vice versa.

I'd probably go for option #2 because of its simplicity, but #1 would work and shouldn't present any problems as long as you've got enough memory in your routers to handle two BGP feeds.

Are you receiving full routes from your ISP?

 

[garycarr]

Yeah, I am taking full routes and have a 7507 with 256MB of ram at site A and a 7206 with 128MB of ram at site B. I plan to upgrade the 7206 to at least 256 if not replace it entirely.

Thanks for any inside into how to configure this.

 

[jneiberger]

Are both sites advertising the same routes to your provider(s)?

 

[garycarr]

Yes they are currently advertising all routes to both upstreams. Currently both DS3s reside in the same router at the same locaion. We are cutting one of the DS3s over to our CO which is in another city.

 

[jneiberger]

If that's the case then you can use either floating static routes or iBGP, depending on whatever other requirements you might have. Keep it as simple as possible, but those solutions are pretty simple.