fix ovs fdb for the local bridge port

[zhangzujian]

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What type of this PR

• Bug fixes

Which issue(s) this PR fixes:

Fixes incorrect mac learning on OVS bridge initialization when hairpin is enabled.

The issue occurs when the node nic contains unicast IPv6 addresses. Delay the port addition, so that ovs-vswitchd can handle IPv6 multicast packets sent back by the switch/bridge:

root@k8s:/kube-ovn# tcpdump -i eth0 -nnvve ip6
tcpdump: listening on eth0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
05:04:54.956995 02:42:ac:14:00:02 > 33:33:00:00:00:16, ethertype IPv6 (0x86dd), length 110: (hlim 1, next-header Options (0) payload length: 56) :: > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener report v2, 2 group record(s) [gaddr ff02::1:ff00:2 to_in { }] [gaddr ff02::1:ff00:0 to_in { }]
05:04:54.957046 02:42:ac:14:00:02 > 33:33:00:00:00:16, ethertype IPv6 (0x86dd), length 110: (hlim 1, next-header Options (0) payload length: 56) :: > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener report v2, 2 group record(s) [gaddr ff02::1:ff00:2 to_in { }] [gaddr ff02::1:ff00:0 to_in { }]
05:04:54.969435 02:42:ac:14:00:02 > 33:33:00:00:00:16, ethertype IPv6 (0x86dd), length 130: (hlim 1, next-header Options (0) payload length: 76) :: > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener report v2, 3 group record(s) [gaddr ff02::1:ff14:2 to_ex { }] [gaddr ff02::1:ff00:2 to_ex { }] [gaddr ff02::2 to_ex { }]
05:04:54.969490 02:42:ac:14:00:02 > 33:33:00:00:00:16, ethertype IPv6 (0x86dd), length 130: (hlim 1, next-header Options (0) payload length: 76) :: > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener report v2, 3 group record(s) [gaddr ff02::1:ff14:2 to_ex { }] [gaddr ff02::1:ff00:2 to_ex { }] [gaddr ff02::2 to_ex { }]