Hmm, I'm not sure where the difference comes from. With Juju 2.9.16 I still see mtu=1442 on VM NIC (expected) and mtu=1450 (bigger than underlying NIC) on fan-252 bridge.
ubuntu@juju-913ba4-k8s-on-openstack-0:~$ brctl show bridge name bridge id STP enabled interfaces fan-252 8000.0653e0778a0a no ftun0 veth966fdd48 lxdbr0 8000.00163e2848ef no ubuntu@juju-913ba4-k8s-on-openstack-0:~$ ip l 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1442 qdisc fq_codel state UP mode DEFAULT group default qlen 1000 link/ether fa:16:3e:27:18:ce brd ff:ff:ff:ff:ff:ff 3: fan-252: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UP mode DEFAULT group default qlen 1000 link/ether 06:53:e0:77:8a:0a brd ff:ff:ff:ff:ff:ff 4: ftun0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1392 qdisc noqueue master fan-252 state UNKNOWN mode DEFAULT group default qlen 1000 link/ether 82:8a:c4:02:b5:77 brd ff:ff:ff:ff:ff:ff 5: lxdbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default qlen 1000 link/ether 00:16:3e:28:48:ef brd ff:ff:ff:ff:ff:ff 7: veth966fdd48@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue master fan-252 state UP mode DEFAULT group default qlen 1000 link/ether 06:53:e0:77:8a:0a brd ff:ff:ff:ff:ff:ff link-netnsid 0 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1936842 Title: agent cannot be up on LXD/Fan network on OpenStack OVN/geneve mtu=1442 To manage notifications about this bug go to: https://bugs.launchpad.net/juju/+bug/1936842/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs