From: Daniel Fredrick (dfredrick@gmail.com)
Date: Sun Sep 24 2006 - 12:51:43 ART
OK... that makes sense, but is there a way to get all of them to have two
routes in the bgp table? Only thing I could think of is that prepending the
as on R6.
Thanks,
Dan
On 9/24/06, Marvin Greenlee <marvingreenlee@yahoo.com> wrote:
>
> 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
> >
> >
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This archive was generated by hypermail 2.1.4 : Sun Oct 01 2006 - 16:55:41 ART