On Wed, Jan 6, 2016 at 12:59 PM, David Miller <da...@davemloft.net> wrote: > From: David Wragg <david@weave.works> > Date: Wed, 6 Jan 2016 13:33:04 +0000 > >> Prior to 4.3, openvswitch vxlan vports could transmit vxlan packets of >> any size, constrained only by the ability to transmit the resulting >> UDP packets. 4.3 introduced vxlan netdevs corresponding to vxlan >> vports. These netdevs have an MTU, which limits the size of a packet >> that can be successfully vxlan-encapsulated. The default value for >> this MTU is 1500, which is awkwardly small, and leads to a conspicuous >> change in behaviour for userspace. >> >> These two patches set the MTU on openvswitch-crated vxlan devices to >> be 65465 (the maximum IP packet size minus the vxlan-on-IPv6 >> overhead), effectively restoring the behaviour prior to 4.3. In order >> to accomplish this, the first patch removes the MTU constraint of 1500 >> for vxlan netdevs without an underlying device. > > Is this really the right thing to do? Won't we get a lot of fragmentation > by using such a large MTU, especially since you're making it the default > for OVS setups? > > Things like path MTU discovery hinge strongly upon accurate MTU settings. > Otherwise they won't function properly.
At a minimum, I don't think this should be VXLAN specific. But I agree that I'm not sure this is the right thing to do. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
