BFD multihop for VNF

[uchard]

I am trying to set up a BFD multihop session for a BGP peering for a service connected (VNF) in a VXLAN fabric on a Nexus 9K to
VNF connected via vPC
Session source loopback interfaces
On one Leaf all sessions are in the UP state, on the other in the DOWN state
All loopback interfaces are reachable for VNF
What could be the cause of this problem?

[M02@rt37]

Hello @uchard,

Do you check routing and connectivity to these loopback addresses from the VNF's perspective ?

[uchard]

Yes, the addresses of both Leafs are accessible from the VNF
We also have a 2 BGP session between VNF and both Leafs in the up state, but only one of the BFD sessions (between VNF and one of Leafs) is up

[M02@rt37]

Ok @uchard.

Do you ensure that BFD settings such as detection times, minimum interval, and authentication match on both ends ?

Verify that the routing paths for BFD packets are symmetric. BFD sessions can fail if there's asymmetric routing.

[uchard]

Both sessions are configured according to a template and the settings are identical
Could there be a problem that both Leafs are members of the same VTEP?