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BGP send back a prefix to the peer which advertised the route.

Not applicable

Hi ALL,

I have a question about bgp advertising prefixes back to the peer which advertised the route.

I am using IOS version 15.2.

My topology is very simple like this:

R3---------------R1--------------R2

R1 belongs to AS 1,R2 and R3 belongs to AS23.

R2 advertise 10.2.1.0/24 to R1 and R3 advertise 10.3.1.0/24 to R1

but when I "show ip bgp nei 1.1.12.2(R2's interface connected to R1) advertised-route , I saw the shown below:

R1#show ip bgp nei 1.1.12.2 advertised-routes

BGP table version is 5, local router ID is 1.1.13.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,

              x best-external, a additional-path, c RIB-compressed,

Origin codes: i - IGP, e - EGP, ? - incomplete

RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path

*>  10.2.1.0/24      1.1.12.2                 0             0 23 i

*>  10.3.1.0/24      1.1.13.3                 0             0 23 i

Total number of prefixes 2

that R1 advertise 10.2.1.0/24 back to R2.

when I shutdown the bgp session between R1 and R3, then R1 didn't advertise this route to R2 anymore.

I don't know why, Can someone help me explain it?

Thanks very much!

1 Reply 1

Deepak Kumar
VIP Alumni
VIP Alumni

Hi,

Please share your BGP configuration.

Regards,

Deepak Kumar

Regards,
Deepak Kumar,
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