CSCvt33438 - VxLAN ARP not updating HMM after VLAN change with same IP

[GerardoJoseHuertaRobles24447]

Hello Everyone,

Recently, We discovered we are hitting this bug CSCvt33438

Scenario:

Site 1:

2 Nexus 9300 series

Site 2:

1 Nexus 9300

Both are extending VLANs using iBGP EVPN VXLAN. For some reason certain VMs (not all VMs) are not reachable from Site 2 despite of belong to the same extended VLAN. Later we discovered that VTEP site 1 was not advertising Route type 2 to VTEP Site 2. Further investigation with TAC We realized we had the same scenarios for CSCvt33438 bug. If anyone else faced this problem and performed the workaround please share your experience and if it was necessary to upgrade to later version. 

It would be really helpful.

[GerardoJoseHuertaRobles24447 · Accepted solution]

I have found a workaround to this problem and maybe for the bug, (at least for me is working), you can force a reprogramming arp entry for the IPs that are not working:

Nexus 9k:

(config-if)# ip arp <ip-address> <mac-address>

(config-if)#no ip arp <ip-address> <mac-address>

After force reprogramming arp entry, we got a new route hmm entry to the host. With the hmm, VTEP 1 was able to advertise route type 2 to the VTEP 2. If you want to check if a host has a hmm entry you can run: "show ip route <ip-address>. At the moment is working for me