On Mon, Jun 20, 2016 at 5:16 AM, Ihar Hrachyshka <ihrac...@redhat.com> wrote: > So back to MTU. When I boot a VM using a VXLAN backed network, the tap device > of MTU=1450 is plugged into the br-int bridge, which lowers the bridge MTU to > 1450. Then when I plug a device that belongs to a GRE network (MTU = 1458) > into that same bridge, the GRE network backed device also gets its MTU > reduced to 1450, and no ‘ip link’ commands allow to raise it to the intended > MTU=1458.
I'm not sure I fully understand the scenario. The part about having multiple, effectively independent networks on the same bridge I understand. I also understand how the bridge device's MTU is lowered to the minimum of the ports attached to the bridge. The part about the tunnel device MTU sounds weird to me. Are these tunnel ports that have been created through OVSDB? Or are they created separately through something like ip link and then attached to OVS just as if they were regular Ethernet devices? In the former case, the ports essentially have infinite MTU so this shouldn't come up at all. And in the latter case, the ports don't even know that they are attached to OVS. (If this is happening, what occurs when you try to change the MTU with ip link? Do you get an error or it just doesn't work?) Finally, what version of OVS and Linux kernel is this happening on? _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
