Comment 4 for bug 1798690

I ran a few tests, trying to reproduce the problem - see below.

I tried 2 flavors, thinking that a small vCPU VM may behave differently, since all of my previous tests were with large VMs. But, this doesn't appear to have any effect since Tests #2 and #3 below show the issue.

Note that Test #1 succeeded, behaving exactly as I would expect.

Note in Test #3, the floating IP stopped responding to pings for over 200 seconds. I didn't have a timer for this, so it could have been 300 seconds, or the time for typical ARP entries to expire. Maybe a gratuitous arp is getting missed somewhere? Since internal traffic is tunneled, it seems unlikely.

Eric

VM flavors:
  c5.xlarge = 4 vCPUs and 8GiB of RAM
  c5.8xlarge = 32 vCPUs and 64GiB of RAM
VM operating system: CentOS 7.5 (1808)
Bash scripts are used for creation and destruction of environment

Test #1 (on Ceph storage) - using c5.xlarge
-------------------------------------------
Create 2 volumes from the CentOS 7.5 (1808) image marked as bootable
Deploy 2 VMs in a domain in a project with the above volumes, respectively
Create an internal network and router and attach router to internal and external network
Assign security groups and a floating IP to both VMs, respectively
Power on 2 VMs
Verify that both VMs are on different physical hosts
Login to VM #1 using floating IP
From VM #1, ping VM #2 on internal network continuously
Ping succeeds
Live migrate VM #2 to a 3rd host
Ping succeeds
Live migrate VM #2 back to original host
Ping succeeds
Live migrate VM #2 back to the 3rd host
Ping succeeds
Ping VM #1 floating IP from outside host
Live migrate VM #2 back to original host
Ping succeeds
Destroy test environment

Test #2 (on Ceph storage) - using c5.8xlarge
--------------------------------------------
Create 2 volumes from the CentOS 7.5 (1808) image marked as bootable
Deploy 2 VMs in a domain in a project with the above volumes, respectively
Create an internal network and router and attach router to internal and external network
Assign security groups and a floating IP to both VMs, respectively
Power on 2 VMs
Verify that both VMs are on different physical hosts
Ping VM #2 floating IP from outside host
Login to VM #1 using floating IP
From VM #1, ping VM #2 on internal network continuously
Live migrate VM #2 to a 3rd host
ERROR: internal ping fails, floating IP ping succeeds
Live migrate VM #2 back to original host
Internal ping resumes, floating IP ping resumes
Live migrate VM #2 to the 3rd host
ERROR: internal ping fails, floating IP ping succeeds
Live migrate VM #2 back to original host
Internal ping resumes, floating IP ping resumes
Destroy test environment

Test #3 (on Ceph storage) - using c5.xlarge (again)
---------------------------------------------------
Create 2 volumes from the CentOS 7.5 (1808) image marked as bootable
Deploy 2 VMs in a domain in a project with the above volumes, respectively
Create an internal network and router and attach router to internal and external network
Assign security groups and a floating IP to both VMs, respectively
Power on 2 VMs
Verify that both VMs are on different physical hosts
Ping VM #2 floating IP from outside host
Login to VM #1 using floating IP
From VM #1, ping VM #2 on internal network continuously
Live migrate VM #2 to a 3rd host
ERROR: Internal ping succeeds, floating IP ping fails
Live migrate VM #2 back to original host
ERROR: Internal ping succeeds, floating IP ping fails
(about 200 seconds goes by)
Floating IP ping works again!
Live migrate VM #2 back to the 3rd host
Both internal and floating IP pings succeed
Live migrate VM #2 back to original host
Both internal and floating IP pings succeed
Live migrate VM #2 back to the 3rd host
Both internal and floating IP pings succeed
Destroy test environment