| 2017-02-17 22:45:41 |
Kent Wu |
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.....
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. |
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. |
|
