Public bug reported: Here is the specific code path I was talking about:
https://github.com/openstack/nova/blob/stable/mitaka/nova/virt/libvirt/vif.py#L531 As you can see in the code, 1. self.plug_ovs_hybrid(instance, vif) -> self._plug_bridge_with_port() which will take care of creation of Linux bridge and setting of MTU properly. 2. however self.plug_ovs_bridge(instance, vif) itself does nothing so MTU is not being set/honored at all. The end-result of this is that the MTU of the VM's tap interface remains 1500 instead of honoring the MTU of the corresponding neutron network.....Note that in this code path we don't need to create the Linux bridge and veth pair at all however we still need to set the MTU properly for the VM tap interface. We believe this is an overlook from this MTU feature patch: https://review.openstack.org/#/c/285710/ Let us know if you need more info then. ** Affects: nova Importance: Undecided Status: New ** Tags: mtu ** Description changed: Here is the specific code path I was talking about: https://github.com/openstack/nova/blob/stable/mitaka/nova/virt/libvirt/vif.py#L531 As you can see in the code, 1. self.plug_ovs_hybrid(instance, vif) -> self._plug_bridge_with_port() which will take care of creation of Linux bridge and setting of MTU properly. 2. however self.plug_ovs_bridge(instance, vif) itself does nothing so MTU is not being set/honored at all. The end-result of this is that the MTU of the VM's tap interface remains 1500 instead of honoring the MTU - of the corresponding neutron network..... + of the corresponding neutron network.....Note that in this code path we + don't need to create the Linux bridge and veth pair at all however we + still need to set the MTU properly for the VM tap interface. We believe this is an overlook from this MTU feature patch: https://review.openstack.org/#/c/285710/ Let us know if you need more info then. -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/1665798 Title: nova-compute is not setting MTU at all when following the plug_ovs_bridge() call path Status in OpenStack Compute (nova): New Bug description: Here is the specific code path I was talking about: https://github.com/openstack/nova/blob/stable/mitaka/nova/virt/libvirt/vif.py#L531 As you can see in the code, 1. self.plug_ovs_hybrid(instance, vif) -> self._plug_bridge_with_port() which will take care of creation of Linux bridge and setting of MTU properly. 2. however self.plug_ovs_bridge(instance, vif) itself does nothing so MTU is not being set/honored at all. The end-result of this is that the MTU of the VM's tap interface remains 1500 instead of honoring the MTU of the corresponding neutron network.....Note that in this code path we don't need to create the Linux bridge and veth pair at all however we still need to set the MTU properly for the VM tap interface. We believe this is an overlook from this MTU feature patch: https://review.openstack.org/#/c/285710/ Let us know if you need more info then. To manage notifications about this bug go to: https://bugs.launchpad.net/nova/+bug/1665798/+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
