Numan is working on this again: https://mail.openvswitch.org/pipermail/ovs-dev/2020-March/368642.html
Ben submitted the patch for the fix and it is merged now upstream in master and branch 2.13 https://github.com/openvswitch/ovs/commit/323ae1e808e6ac503f5c7ddd50a79d908fdd0e41
tested on openvswitch2.13.0-9: :: [ 21:47:59 ] :: [ BEGIN ] :: Running 'ip netns exec fake_vm2 ping6 -I fake_vm2 fd01::28e7:a3ff:fe00:5 -c 5' PING fd01::28e7:a3ff:fe00:5(fd01::28e7:a3ff:fe00:5) from fd01::28e7:a3ff:fe00:8 fake_vm2: 56 data bytes 64 bytes from fd01::28e7:a3ff:fe00:5: icmp_seq=1 ttl=64 time=3.30 ms 64 bytes from fd01::28e7:a3ff:fe00:5: icmp_seq=2 ttl=64 time=0.906 ms 64 bytes from fd01::28e7:a3ff:fe00:5: icmp_seq=3 ttl=64 time=0.114 ms 64 bytes from fd01::28e7:a3ff:fe00:5: icmp_seq=4 ttl=64 time=0.107 ms 64 bytes from fd01::28e7:a3ff:fe00:5: icmp_seq=5 ttl=64 time=0.112 ms --- fd01::28e7:a3ff:fe00:5 ping statistics --- 5 packets transmitted, 5 received, 0% packet loss, time 4002ms rtt min/avg/max/mdev = 0.107/0.908/3.303/1.236 ms :: [ 21:48:03 ] :: [ PASS ] :: Command 'ip netns exec fake_vm2 ping6 -I fake_vm2 fd01::28e7:a3ff:fe00:5 -c 5' (Expected 0, got 0) :: [ 21:48:03 ] :: [ BEGIN ] :: Running 'dmesg | grep -E "Key type.*is out of range"' :: [ 21:48:03 ] :: [ PASS ] :: Command 'dmesg | grep -E "Key type.*is out of range"' (Expected 1, got 1) <=== no error in dmesg [root@dell-per740-12 bz1775778_kernel_unknown_flow]# rpm -qa | grep -E "openvswitch|ovn" kernel-kernel-networking-openvswitch-ovn-regression-bz1775778_kernel_unknown_flow-1.0-1.noarch openvswitch-selinux-extra-policy-1.0-15.el7fdp.noarch ovn2.13-host-2.13.0-7.el7fdp.x86_64 kernel-kernel-networking-openvswitch-ovn-common-1.0-7.noarch ovn2.13-central-2.13.0-7.el7fdp.x86_64 ovn2.13-2.13.0-7.el7fdp.x86_64 openvswitch2.13-2.13.0-9.el7fdp.x86_64
set VERIFIED per comment 6