VXLAN EVPN Alternate path not working

[Amit M.]

Hi,

I have a lab where I have deployed a triangle of bgp evpn NXOS 9000v switches. On each side of the triangle a have a host.

Lets say the following:

Host A with mac a.a.a.a in side A of the triangle

Host B with mac b.b.b.b in side B of the triangle

Host C with mac c.c.c.c in side C of the triangle

All hosts are in the same subnet and all VTEPs as different ASs, so this is all eBGP.

Host A can reach host B and C perfectly going through its directly connected link from its VTEP. 

The problem comes that, when I disconnect for instance link from VTEP between host A and host B. I can still reach host C but unable to reach host B eventhough through BGP EVPN table I see AS B + C. The VTEPs has the l2route mac installed on each side and when I check the packets in wireshark I can see the packet flowing through the triangle but no response back. The same happens if I try to ping from host C to A. Packet ICMP reahes from C to A, but no response...

Any clue what Im missing.

I think that im missing a command that when in the AS path when there is 2 or more ASs in the path I should allow it...

Please help

Thanks

Amit

[Amit M.]

Just to clarify

Underlay is OSPF area 0

Overlay is eBGP

Route target import and exports are correct as I have full reachability when all 3 links are up

Thanks and best regards

Amit

[Abzal]

Could be a bug. Have you checked in a bug tracker? What is NX-OS version and model of the leaves?

[Amit M.]

Hi Abzal,

Thanks for your reply.

The version of the VIRL nodes is 9.2.3 NX-OSv

I´ve looked at the documentation and I wasn´t able to find something about this issue.

I think yes, you are correct, I can imagine this is a bug because, if I do show commands, the control-plane is correct but the data-plane doesn´t behave as expected. In other words, my personal conclusion that this is a data-plane bug.

Best regards

Amit