Public bug reported: Hi all. We have seen this behavior when using OVS ML2 plugin in a Kolla- based deployed OpenStack. Basically, when changing the MTU of an existing network, the change is not applied to already-bound Open vSwitch ports.
The steps to reproduce are pretty straightforward: 1. Create an OVS network with MTU 1300. 2. Create a subnet, and deploy a virtual machine on it. 3. Change the network's MTU to 1400. If you then check the MTU for the previous OVS port (i.e. ovs-vsctl list interface) it will still be 1300. This only affects existing ports. Newly created ports will use the newer MTU. Workaround is to manually change the MTU (i.e. ovs-vsctl set int <interface> mtu_request=1400) or to detach and re-attach the ports. Looking at the ML2 plugin.py code (at https://opendev.org/openstack/neutron/src/branch/master/neutron/plugins/ml2/plugin.py#L1305 ) it appears that each agent should update the MTU for their ports. ** Affects: neutron Importance: Undecided Status: New -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to neutron. https://bugs.launchpad.net/bugs/2101087 Title: [ovs] MTU change is not applied to existing openvswitch ports Status in neutron: New Bug description: Hi all. We have seen this behavior when using OVS ML2 plugin in a Kolla-based deployed OpenStack. Basically, when changing the MTU of an existing network, the change is not applied to already-bound Open vSwitch ports. The steps to reproduce are pretty straightforward: 1. Create an OVS network with MTU 1300. 2. Create a subnet, and deploy a virtual machine on it. 3. Change the network's MTU to 1400. If you then check the MTU for the previous OVS port (i.e. ovs-vsctl list interface) it will still be 1300. This only affects existing ports. Newly created ports will use the newer MTU. Workaround is to manually change the MTU (i.e. ovs-vsctl set int <interface> mtu_request=1400) or to detach and re-attach the ports. Looking at the ML2 plugin.py code (at https://opendev.org/openstack/neutron/src/branch/master/neutron/plugins/ml2/plugin.py#L1305 ) it appears that each agent should update the MTU for their ports. To manage notifications about this bug go to: https://bugs.launchpad.net/neutron/+bug/2101087/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
