On 12/02/14 at 07:34pm, Michael S. Tsirkin wrote: > On Tue, Dec 02, 2014 at 05:09:27PM +0000, Thomas Graf wrote: > > On 12/02/14 at 01:48pm, Flavio Leitner wrote: > > > What about containers or any other virtualization environment that > > > doesn't use Virtio? > > > > The host can dictate the MTU in that case for both veth or OVS > > internal which would be primary container plumbing techniques. > > It typically can't do this easily for VMs with emulated devices: > real ethernet uses a fixed MTU. > > IMHO it's confusing to suggest MTU as a fix for this bug, it's > an unrelated optimization. > ICMP_DEST_UNREACH/ICMP_FRAG_NEEDED is the right fix here.
PMTU discovery only resolves the issue if an actual IP stack is running inside the VM. This may not be the case at all. I agree that exposing an MTU towards the guest is not applicable in all situations, in particular because it is difficult to decide what MTU to expose. It is a relatively elegant solution in a lot of virtualization host cases hooked up to an orchestration system though. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
