VxLAN traffic not offloaded

Issue

• Traffic from instances in VxLAN networks is not being offloaded. We are using OSP13 z9 with OVS 2.11 sideloaded.

• Traffic is seen on the interface where as in the past, that traffic would only be seen iwthin the guest itself:

[root@overcloud-compute-1 heat-admin]# tcpdump -nni "enp175s0f1_2"
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on enp175s0f1_2, link-type EN10MB (Ethernet), capture size 262144 bytes
20:00:17.616706 ARP, Request who-has 10.10.10.10 tell 10.10.10.20, length 46
20:00:17.617013 ARP, Reply 10.10.10.10 is-at fa:16:ff:ff:ff:ff, length 46
20:00:17.617073 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 1, length 64
20:00:17.705283 IP 10.10.10.10 > 10.10.10.20: ICMP echo reply, id 22960, seq 1, length 64
20:00:18.618203 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 2, length 64
20:00:19.619344 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 3, length 64
20:00:20.621355 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 4, length 64
20:00:21.623342 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 5, length 64
20:00:22.624752 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 6, length 64
20:00:23.626706 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 7, length 64
20:00:24.628687 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 8, length 64
20:00:25.630520 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 9, length 64
20:00:26.632400 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 10, length 64
20:00:27.634304 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 11, length 64
20:00:28.636213 IP 10.10.10.20 > 10.10.10.10: ICMP echo request, id 22960, seq 12, length 64

• We are also using IPv6 for VxLAN endpoints and the VxLAN tunnel endpoint is on VLAN interface (VxLAN over VLAN).

• This setup works in OSP 13 z8. Something changed recently which is causing this.