BGP Neighbour Issues

[petenixon]

Hi all,

I'm having problems establishing an adjacency between a 3750-x running bgp and a remote (directly connected) router. The adjacency is failing with the error: ADJ-3-RESOLVE_REQ: Adj resolve request: Failed to resolve 10.44.163.171 Vlan212 (10.44.163.171 is a HSRP address), I can see this in the ARP cache on the switch and the address is pingable. Switch is running 15.2(SE7). 

Basic BGP config on the switch:

router bgp xxxx
neighbor 10.44.163.169 remote-as xxxx

I can ping the .169 (and .171 address).

Any insights would be appreciated before I speak to the 3rd party maintaining the remote router.

Thanks.

[paul driver]

Hello

its a directly connected router but not a directly connected interface- correct ?

if so try using

update-source 

Ebgp multihop 

commands in th Ebgp process 

re

paul

[petenixon]

Hi Paul,

Thanks for the reply, I did try those commands earlier but had no effect. Output of a debug convinces me that the issue is with the remote end:

Mar 30 03:07:51.121: BGP: 10.44.163.169 open failed: Connection refused by remote host
 

Thanks

[paul driver]

Hello

then authentiction could be  possible cause

have you checked with the bfp peer?

rs

paul

[petenixon]

Thanks again for coming back to me so quickly Paul, it is very much appreciated.

I am waiting for the remote site engineer to contact me so I can verify the config of the remote peer. Once I have done that I think I will have a better understanding of what the issue might be.

[Jon Marshall]

Pete

If you are using the HSRP VIP on your side and that is what they have configured as the neighbor IP address in their BGP configuration then you probably won't be able to initiate the connection

This is because if you start the connection your switch uses the source IP of the physical interface and that doesn't match the neighbor IP they have configured on their device.

If you want to use the HSRP VIP then the remote device needs to initiate the connection and you need to make your end passive ie. it does not try to open the connection.

This should work because the initial connection is to the HSRP VIP and so the response comes from that IP as well although we did have a discussion a while back as to how well this works if HSRP fails over in terms time taken to bring up a new BGP session.

Try adding this to your configuration and then have the other side try to initiate the connection -

"neighbor 10.144.163.169  transport connection-mode passive"

obviously the remote device can't also be using HSRP and can't be using the above command or it will never work.

Jon

[petenixon]

Hi Jon,

Yep, the remote router has the hsrp vip configured, and i'm still waiting for them to verify the config! Your assistance is still very much appreciated.

Cheers,
Pete.

[petenixon]

Thanks all for your suggestions, turns out it was indeed the remote router config that was the issue!

Cheers.

[Jon Marshall]

Actually Pete I may have got it wrong in terms of what you are trying to do.

I was assuming the VIP was on your end but rereading it perhaps not ?

Jon

[paul driver]

Hello.

you could also probably try to  negate the bgp validation check

with the  neighbour x.x.x.x disable-connected-check

command

res

paul