Brian, I think you could either configure R2 and R3 for bgp or use conditional advertisement to inject the default route from R1 and R4(please search CCO for this). Of course, you want to make R1 the preferred exit point.
HTHs Kent ----- Original Message ----- From: "brian kastor" To: Sent: Friday, June 14, 2002 8:23 AM Subject: Sonet, 2 isp's, 2 sites [7:46565] > All, > > I have 2 sites. We currently get full routing tables from uunet and AT&T > into a single router. We want to put a second router at another site and > run IBGP between just those two. We will have two routers between the two > running BGP. I guess it would look something like this: > > site1-r1(bgp)---r2---r3---r4(bgp)-site2 > > R1 will get UUnet, r4 will get at&t. R1(UUNet) is being used as primary. > Behind R1 is our HQ. Behind r4 is a large branch. > My concern would be if the link to UUnet goes down, how does traffic from > site 1 get out r4. > > Scenario: > User pings 12.x.x.x This is unknown on site 1, so it goes to r1. UUnet is > down, so the route is pointing to r4 (ibgp). The packet still has a > destination address of 12.x.x.x, but how does r2 know what to do with this > packet? It doesn't know where 12.x.x.x is? > > Someone here at work brought this up to me and I keep saying that the ibgp > session gets established, so when you look at the table on r1 for 12.x.x.x, > the next hop is the interface of r4. He keeps saying, 'yeah, but when that > packet gets to r2, the destination is 12.x.x.x, which it doesn't know.' > > All of this can be solved if someone tells me that we just need to run ibgp > on all 4 routers and i shouldn't see a performance hit. I am worried > because these routers are going to be routing user traffic between the sites. > > Thanks, > > bk Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=46605&t=46565 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
