[ovs-dev] [PATCH ovn v2] ovn-nb: Document LRP gateway_mtu option

Frode Nordahl frode.nordahl at canonical.com
Tue Nov 9 10:11:58 UTC 2021

The Logical Router Port gateway_mtu option is currently only
documented together with implementation details in the ovn-northd

As this is CMS API we ought to document this as part of the OVN
Northbound Database as well.

Reported-at: https://github.com/ovn-org/ovn/issues/78
Fixes: 7d42c14 ("ovn: Generate ICMPv4 packet in router pipeline for larger packets")
Signed-off-by: Frode Nordahl <frode.nordahl at canonical.com>
 ovn-nb.xml | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/ovn-nb.xml b/ovn-nb.xml
index 036ffa64f..bb0970e94 100644
--- a/ovn-nb.xml
+++ b/ovn-nb.xml
@@ -2820,6 +2820,19 @@
           prefix according to RFC3663
+      <column name="options" key="gateway_mtu"
+          type='{"type": "integer", "minInteger": 68, "maxInteger": 65535}'>
+        <p>
+          If set, logical flows will be added to router pipeline to check
+          packet length.  If packet length is greater than the value set,
+          ICMPv4 type 3 (Destination Unreachable) code 4 (Fragmentation Needed
+          and Don't Fragment was Set) or ICMPv6 type 2 (Packet Too Big)
+          code 0 (no route to destination) packets will be generated.
+          This allows for Path MTU Discovery.
+        </p>
+      </column>
     <group title="Attachment">

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