[bagpipe_bgpvpn] restart ovs agent only will lose flows

[LIU Yulong]

Flows in table 20 and 21 will not recover if ovs agent is restarted. The following are the flows before restart the ovs-agent. After restart ovs-agent, these flows are gone.

$ sudo ovs-ofctl dump-flows br-tun table=20
 cookie=0xf1f1ad5ed8b1ae9f, duration=233196.361s, table=20, n_packets=0, n_bytes=0, priority=5,dl_vlan=1,dl_dst=fa:16:3e:05:ac:84 actions=strip_vlan,load:0x44->NXM_NX_TUN_ID[],output:"vxlan-1400140b"
 cookie=0xf1f1ad5ed8b1ae9f, duration=233196.190s, table=20, n_packets=110, n_bytes=45780, priority=5,dl_vlan=1,dl_dst=fa:16:3e:46:58:fe actions=strip_vlan,load:0x44->NXM_NX_TUN_ID[],output:"vxlan-1400140b"

$ sudo ovs-ofctl dump-flows br-tun table=21
 cookie=0xf1f1ad5ed8b1ae9f, duration=233198.918s, table=21, n_packets=0, n_bytes=0, priority=1,arp,dl_vlan=1,arp_tpa=192.168.111.199 actions=move:NXM_OF_ETH_SRC[]->NXM_OF_ETH_DST[],mod_dl_src:fa:16:3e:05:ac:84,load:0x2->NXM_OF_ARP_OP[],move:NXM_NX_ARP_SHA[]->NXM_NX_ARP_THA[],move:NXM_OF_ARP_SPA[]->NXM_OF_ARP_TPA[],load:0xfa163e05ac84->NXM_NX_ARP_SHA[],load:0xc0a86fc7->NXM_OF_ARP_SPA[],IN_PORT
 cookie=0xf1f1ad5ed8b1ae9f, duration=233198.744s, table=21, n_packets=0, n_bytes=0, priority=1,arp,dl_vlan=1,arp_tpa=192.168.111.99 actions=move:NXM_OF_ETH_SRC[]->NXM_OF_ETH_DST[],mod_dl_src:fa:16:3e:46:58:fe,load:0x2->NXM_OF_ARP_OP[],move:NXM_NX_ARP_SHA[]->NXM_NX_ARP_THA[],move:NXM_OF_ARP_SPA[]->NXM_OF_ARP_TPA[],load:0xfa163e4658fe->NXM_NX_ARP_SHA[],load:0xc0a86f63->NXM_OF_ARP_SPA[],IN_PORT

Ovs agent config option:

[agent]
l2_population = False
arp_responder = False
extensions = bagpipe_bgpvpn

[Lajos Katona (lajos-katona)]

The proposed patch: https://review.opendev.org/c/openstack/networking-bagpipe/+/781604

[LIU Yulong (dragon889)]

An alternative fix in neutron side, skipping the related flow clean during the ovs-agent restart:
https://review.opendev.org/c/openstack/neutron/+/782345

[OpenStack Infra (hudson-openstack)]

Change abandoned by "liuyulong <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/networking-bagpipe/+/781604