[DUAL STACK]BGP v4 Peering on Cisco ACI

[ecsnnsls]

Hi,

In our environment, we have an existing v6 BGP peer setup and operational. We wanted to enable v4 on the same L3OUT.

So I created a new Logical Interface Profile for v4 and configured BGP. The configurations were pushed without any faults.

The problem that I am facing is that I don't see any BGP peers under the "Configured Nodes" section and under the command "show bgp ipv4 unicast summary vrf <vrfname>"

On the remote end, the status of the ACI TOR peer is "CONNECT". One other observation is that under the command vsh show ip bgp neighbors vrf <vrfname>  I see the following output,

BGP prefix peer <v4peerIP>, remote AS <RASN>, ebgp link
Only passive connection setup allowed
Active peers 0 (0 closing), Maximum concurrent peers 0
Total peers accepted 0

 TLDR, BGP peer is not visible under "configured nodes" on a dual stack l3out and no peers are visible under the command show bgp ipv4 unicast summary vrf <vrfname>

[nileshgore25]

I think this is expected, when the peer is down.

In my case I was able to see the BGP neighbor via CLI in idle state for sometime immediately after I pushed the configuration. And the entries got cleared after few minutes.

the neighbor entry should show as soon as the session is established.

[ecsnnsls]

Thank you for responding, in my case the peer also was also on passive mode so the BGP peering never came up.

Once the peer was switched to active, the BGP peering came up. I am currently on the search of a relevant setting or knob on ACI where we can control the mode of BGP peering. Thanks again for your response.

[ahmedtaha4]

Hi , 

What is the status of ICMP reachability ? , and Ensure that L3EPG configured.

[ecsnnsls]

Hi Ahmed,

It's an L3OUT and ICMP works fine. The problem is BGP is a passive speaker in the case of ACI and there's no way I could flip it to active.

I had to configure the peer to be an active peer for the BGP to come up. Also note that, the BGP peering for v6 is already UP and established.