From: Marvin Greenlee (marvingreenlee@yahoo.com)
Date: Sun Sep 24 2006 - 12:47:17 ART
Is the issue that R5 and R6 are removing them or that
R1 isn't advertising them? Debug your BGP updates. I
would guess that R1 isn't advertising them to R5,
because his best path for the networks is the route
learned via R5. R1 is only going to advertise his
best path. When the other link drops, R1's best path
is via AS254 directly, and he will advertise that to
R5 and R6.
Thanks,
Marvin
--- Daniel Fredrick <dfredrick@gmail.com> wrote:
> Here's the BGP topology...
>
> AS254 AS254
> (BB1) (BB2)
> | |
> | RR |
> (R1)---------(R5)-----------(R6)
> AS3 AS3 AS3
>
> R5 is the route reflector.
>
> OK... now BB1 and BB2 are sending the same BGP
> routes. The only difference
> is BB1 is sending the same routes is an aspath of
> "254 253". BB2 is sending
> the same routes, but with an aspath of just "254"
>
> OK... so here's my problem. When I do a "show ip
> bgp" all of the routers
> don't show both routes from BB1 and BB2.
>
> R1 shows both routes from BB1 and BB2, with BB2
> routes preferred... since it
> has a shorter BGP path.
>
> R5 only shows only BB2 routes.
>
> R6 only shows BB2 routes.
>
> So... here comes the confusing part...
>
> When R5 loses R6 as a bgp neighbor and it is down,
> the routes from BB2
> disappear in "show ip bgp" and the routes from BB1
> show up in "show ip bgp"
>
> So what could cause R5 and R6 to remove the routes
> from the bgp table? It
> should keep them in there... but just not use them
> as a preferred route.
>
> Thanks,
> Dan
>
>
This archive was generated by hypermail 2.1.4 : Sun Oct 01 2006 - 16:55:41 ART