I tried to reproduce this bug in the virtual machine, but I can't reproduce this bug on duplex system using 1030 iso image and OVS. I create an instance and live migration between controller-0 and controller-1. When I ping the instance ip in the network namespace multiple times, I can always ping successfully. The log is as following： controller-0:~$ openstack server create --image cirros --flavor m1.tiny --network public-net0 vm1 --security-group security1 controller-0:~$ openstack server show vm1 +-------------------------------------+----------------------------------------------------------+ | Field | Value | +-------------------------------------+----------------------------------------------------------+ | OS-DCF:diskConfig | MANUAL | | OS-EXT-AZ:availability_zone | nova | | OS-EXT-SRV-ATTR:host | controller-0 | | OS-EXT-SRV-ATTR:hypervisor_hostname | controller-0 | | OS-EXT-SRV-ATTR:instance_name | instance-00000020 | | OS-EXT-STS:power_state | Running | | OS-EXT-STS:task_state | None | | OS-EXT-STS:vm_state | active | | OS-SRV-USG:launched_at | 2019-11-11T06:43:36.000000 | | OS-SRV-USG:terminated_at | None | | accessIPv4 | | | accessIPv6 | | | addresses | public-net0=192.168.101.124 | | config_drive | | | created | 2019-11-11T06:43:22Z | | flavor | m1.tiny (8f06630c-5562-45cb-8388-1cacc54a0db8) | | hostId | d6a9ce7a8bce088e58adce0b116bac1932e3c4c95e3f1d41b749e3dc | | id | e3e51909-b05b-483b-822b-2f719c6b598e | | image | cirros (271e62a3-f3fd-47ad-aa06-de9f1dbcdb0a) | | key_name | None | | name | vm1 | | progress | 0 | | project_id | 820c5ebe5a164087815efc522ce79920 | | properties | | | security_groups | name='security1' | | status | ACTIVE | | updated | 2019-11-11T14:07:54Z | | user_id | d5f192203ca04ce5823cf5c45d098fa4 | | volumes_attached | | +-------------------------------------+----------------------------------------------------------+ controller-0:~$ openstack server migrate vm1 --live controller-1 --block-migration controller-0:~$ openstack server show vm1 +-------------------------------------+----------------------------------------------------------+ | Field | Value | +-------------------------------------+----------------------------------------------------------+ | OS-DCF:diskConfig | MANUAL | | OS-EXT-AZ:availability_zone | nova | | OS-EXT-SRV-ATTR:host | controller-1 | | OS-EXT-SRV-ATTR:hypervisor_hostname | controller-1 | | OS-EXT-SRV-ATTR:instance_name | instance-00000020 | | OS-EXT-STS:power_state | Running | | OS-EXT-STS:task_state | None | | OS-EXT-STS:vm_state | active | | OS-SRV-USG:launched_at | 2019-11-11T06:43:36.000000 | | OS-SRV-USG:terminated_at | None | | accessIPv4 | | | accessIPv6 | | | addresses | public-net0=192.168.101.124 | | config_drive | | | created | 2019-11-11T06:43:22Z | | flavor | m1.tiny (8f06630c-5562-45cb-8388-1cacc54a0db8) | | hostId | d6a9ce7a8bce088e58adce0b116bac1932e3c4c95e3f1d41b749e3dc | | id | e3e51909-b05b-483b-822b-2f719c6b598e | | image | cirros (271e62a3-f3fd-47ad-aa06-de9f1dbcdb0a) | | key_name | None | | name | vm1 | | progress | 0 | | project_id | 820c5ebe5a164087815efc522ce79920 | | properties | | | security_groups | name='security1' | | status | ACTIVE | | updated | 2019-11-11T15:58:34Z | | user_id | d5f192203ca04ce5823cf5c45d098fa4 | | volumes_attached | | +-------------------------------------+----------------------------------------------------------+ controller-0:~$ ip netns qrouter-9d28512d-1024-41b5-9b3a-7444dd3eedc0 (id: 33) qrouter-1623c1ed-9a68-4b52-afbf-89b01e77007f (id: 22) qdhcp-fa426efa-2282-4c84-9d5c-799e118ed283 (id: 30) qdhcp-10367735-8509-4c1c-9132-e1bb980bc400 (id: 28) qdhcp-3b8372e7-8ac0-4960-8d75-57d63cda01c8 (id: 20) controller-0:~$ sudo ip netns exec qrouter-1623c1ed-9a68-4b52-afbf-89b01e77007f ping 192.168.101.124 PING 192.168.101.124 (192.168.101.124) 56(84) bytes of data. 64 bytes from 192.168.101.124: icmp_seq=1 ttl=64 time=7.03 ms 64 bytes from 192.168.101.124: icmp_seq=2 ttl=64 time=2.12 ms 64 bytes from 192.168.101.124: icmp_seq=3 ttl=64 time=1.31 ms 64 bytes from 192.168.101.124: icmp_seq=4 ttl=64 time=1.26 ms 64 bytes from 192.168.101.124: icmp_seq=5 ttl=64 time=1.37 ms 64 bytes from 192.168.101.124: icmp_seq=6 ttl=64 time=0.889 ms 64 bytes from 192.168.101.124: icmp_seq=7 ttl=64 time=1.49 ms 64 bytes from 192.168.101.124: icmp_seq=8 ttl=64 time=1.70 ms 64 bytes from 192.168.101.124: icmp_seq=9 ttl=64 time=1.26 ms 64 bytes from 192.168.101.124: icmp_seq=10 ttl=64 time=1.26 ms 64 bytes from 192.168.101.124: icmp_seq=11 ttl=64 time=1.22 ms 64 bytes from 192.168.101.124: icmp_seq=12 ttl=64 time=1.24 ms 64 bytes from 192.168.101.124: icmp_seq=13 ttl=64 time=1.07 ms ^C --- 192.168.101.124 ping statistics --- 13 packets transmitted, 13 received, 0% packet loss, time 12016ms rtt min/avg/max/mdev = 0.889/1.790/7.037/1.541 ms