[ovs-discuss] mtu setting lost

Andreas Pflug pgadmin at pse-consulting.de
Mon Nov 11 09:39:42 UTC 2013


I'm running ovs (1.4.2) for xen bridging from debian 7.1.

The physical interface is configured to the max possible MTU of 9216,
because there's one ovs port configured for san access with a VLAN tag
and MTU of 9190 that's used by open-iscsi initiator exclusively. The
machine's main/management interface is configured to default MTU 1500.

If I start a VM, its VIFs will be created with MTU=1500. When they are
added to the ovs bridge, subsequently all non-physical interfaces will
be reset to MTU=1500, including the (for common network traffic unused)
san port. The same will happen if I further reduce one interface MTU
manually; its setting will propagate to all ports. This appears
unexpected to me and is undesirable.

How can I avoid this?

Regards
Andreas



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