Since [1][2], the gateway router port will have the option ``gateway_mtu`` set if the configuration variable ``[ovn]ovn_emit_need_to_frag`` is set, using the minimum MTU value of all networks connected to the router. That will limit the N/S traffic MTU regardless if the gateway network MTU is greater or less than the internal network MTU. [1]https://bugs.launchpad.net/neutron/+bug/2032817 [2]https://review.opendev.org/c/openstack/neutron/+/937026 Documentation Signed-off-by: Rodolfo Alonso Hernandez <ralonsoh@redhat.com> Change-Id: I17d3cb3a36fb1e0f7e1ec36b523361b61f9cdadf