Comment 2 for bug 1905933

With a focal deployment as deployed by the OpenStack Charms using the in-distro released packages I can have a instance created with a floating IP and confirm it is able to reach the Ubuntu archive:

$ chmod 600 /tmp/zaza-467221d1afd6/id_rsa_zaza
$ ssh -i /tmp/zaza-467221d1afd6/id_rsa_zaza ubuntu@10.78.95.103
ubuntu@zaza-neutrontests-ins-1:~$ ping archive.ubuntu.com
PING archive.ubuntu.com (91.189.88.142) 56(84) bytes of data.
64 bytes from aerodent.canonical.com (91.189.88.142): icmp_seq=1 ttl=60 time=74.3 ms
64 bytes from aerodent.canonical.com (91.189.88.142): icmp_seq=2 ttl=60 time=67.5 ms
^C
--- archive.ubuntu.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 67.568/70.938/74.308/3.370 ms

If I then enable Distributed Floatring IP for OVN by issuing the following command and wait for deployment to settle:
$ juju config neutron-api-plugin-ovn enable-distributed-floating-ip=true

I can then repeat the attempt to reach the Ubuntu archive:
ubuntu@zaza-neutrontests-ins-1:~$ ping archive.ubuntu.com
PING archive.ubuntu.com (91.189.88.152) 56(84) bytes of data.
^C
--- archive.ubuntu.com ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2032ms

Dumping packets on the external port of the hypervisor for the instance I can see:
# tcpdump -nevvi enp6s0 arp
tcpdump: listening on enp6s0, link-type EN10MB (Ethernet), capture size 262144 bytes
16:37:54.290577 fa:16:3e:fa:6a:11 > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Ethernet (len 6), IPv4 (len 4), Request who-has 91.189.88.152 tell 10.78.95.103, length 28

Adding -proposed to ovn-central and hypervisor units:
juju run --application ovn-central 'sudo sh -c "echo deb http://archive.ubuntu.com/ubuntu focal-proposed multiverse restricted main universe >> /etc/apt/sources.list"'
juju run --application ovn-central 'apt update'
juju run --application ovn-central 'sudo apt -y install ovn-central ovn-common'
juju run --application neutron-api 'systemctl restart neutron-server'

for machine in 0 1 2; do juju run --machine $machine 'sudo sh -c "echo deb http://archive.ubuntu.com/ubuntu focal-proposed multiverse restricted main universe >> /etc/apt/sources.list"'&done
for machine in 0 1 2; do juju run --machine $machine 'sudo apt update'&done
for machine in 0 1 2; do juju run --machine $machine 'sudo apt -y install ovn-common ovn-host'&done
wait

I can now repeat the attempt to ping the Ubuntu archive from my instance:
ubuntu@zaza-neutrontests-ins-1:~$ ping archive.ubuntu.com
PING archive.ubuntu.com (91.189.88.142) 56(84) bytes of data.
64 bytes from aerodent.canonical.com (91.189.88.142): icmp_seq=1 ttl=60 time=44.5 ms
64 bytes from aerodent.canonical.com (91.189.88.142): icmp_seq=2 ttl=60 time=43.8 ms
^C
--- archive.ubuntu.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1002ms
rtt min/avg/max/mdev = 43.883/44.197/44.512/0.378 ms

Success!