How to verify if your BGP Peer is receiving your advertised-routes?

[thestudent]

Hi,

Is there any Cisco Router command that will verify if your BGP peer is receiving the the routes you are advertising?

With #show ip bgp neighbor x.x.x.x advertised-routes - you can check the routes you are advertising.

But you have to go to the other router, which is your peer, to check if they are receiving it via command:

#show ip bgp neighbors x.x.x.x received-routes given that soft reconfiguration is enabled.

My question is, is there a way to check on my router to verify if my peer is receiving the routes I advertised?

[Georg Pauwen]

Hello,

unless you configure some sort of preset response that is sent by the receiving router to the sending router, which requires access to the receiving router, I don't see how the sending router can verify that.

[Giuseppe Larosa · Accepted solution]

Hello @thestudent ,

BGP is based on TCP using the well known port TCP 179 on one side.

The BGP updates are sent in TCP segments and these segments are acknowledged at TCP level.

It is not a direct information but the sending BGP router is informed at TCP level that all its BGP prefixes have been received by TCP ACK field with appropriate sequence number.

TCP provides a reliable transport service of bytes/octects  in order.

So I would say this is enough to know the NLRIs have been received by the peer.

The peer can use an inbound filter to accept only of subset of sent prefixes, but this is another matter.

Hope to help

Giuseppe