[ovs-discuss] OVN vm on vlan network using geneve tunnel for external traffic

Ben Pfaff blp at ovn.org
Fri Apr 13 21:27:03 UTC 2018

On Wed, Apr 11, 2018 at 07:44:25PM +0530, Anil Venkata wrote:
> vm created on a vlan tenant network is using geneve tunnel(between compute
> and gateway nodes) to reach external network. Because of this, we need to
> consider tunnelling overhead while assigning MTU for vlan network. Can we
> improve OVN to avoid tunnelling in this case.

When OVN tunnels packets, the tunnel metadata includes information on
the logical network, logical input port, and logical output port.  The
logical input port is only used for egress ACLs, so it could be omitted
if egress ACLs are constrained not to match on the logical input port.
The logical network and logical output port are still needed, though, so
to encode that in a VLAN they would have to add up to 12 bits or less.
That's pretty constraining.  Do you have some idea for how to do it?

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