No return traffic from BGP peer on ASR1001-X

[ThinMan]

Hello, 

I have a upgraded one our public facing routers from 2951 to ASR1001-X. Since then I have connectivity issues with one of our BGP neighbors. The problem is, no return traffic is received from the neighbour.

- BGP peering works 

- Receiving expected routes from the peer

- Peer can receive my advertised routes with correct med 

- Traffic destined towards the peer is blackholed. On traceroute, I can see the trace up to neighhour router but then it stops. 

There is no ACL applied to the Interface, no TCP block etc. 

We have another BGP session on the same router, with a different peer, which works okay. 

Not sure what part of the configuration to share, let me know if you need any specific configurations ?  

[paul driver]

Hello

So you are receiving prefixes from this bgp peer but your'e experiencing asymmetric traffic patterns

sh ip bgp neighbours x.x.x.x

sh ip bgp neighbours  x.x.x.x routes
sh ip bgp neighbours  x.x.x.x advertised-routes
sh ip bgp
sh ip bgp sum
sh ip route bgp