yahoo-eng-team team mailing list archive

[Rodolfo Alonso <2101087@xxxxxxxxxxxxxxxxxx>]

Hello Alejandro:

This is not a bug. When Nova defines the VM XML, it retrieves the
current port/network information and defines the TAP interface with the
current MTU value. If the network MTU is updated, the VM XML definition
won't be.

In order to change the TAP MTU, it is needed to detach and re-attach
again the interface or reboot the VM.

Regards.

** Changed in: neutron
       Status: New => Invalid

-- 
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:
  Invalid

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