controller: Flood local IGMP/MLD queries in L2 domain only. - #324
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Locally generated IGMP/MLD membership queries were injected into OFTABLE_LOCAL_OUTPUT with outport set to MC_FLOOD. That floods the query to every local port, including patch ports towards logical routers. In scaled topologies with many VIFs and/or many connected routers, the nested resubmits exceed OVS's 4096 resubmit limit and the packet-out is dropped. Snooped queries are already re-injected with MC_FLOOD_L2. Use the same key for locally generated queries so they stay in the L2 broadcast domain (RFC 4541) and skip router ports that would drop the traffic anyway. Reported-at: https://issues.redhat.com/browse/OCPBUGS-114016 Signed-off-by: Trushna Deokar <tdeokar@redhat.com> Co-authored-by: Cursor <cursoragent@cursor.com>
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Thanks for the contribution, @DeokarT! As discussed privately, it's probably better if you post this as a patch to our development mailing list, as documented in our guidelines: https://github.com/ovn-org/ovn/blob/main/Documentation/internals/contributing/submitting-patches.rst Feel free to CC me on the patch or to reach out if you face any issues while doing that. Regards, |
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Closing in favor of a mailing-list submission to dev@openvswitch.org per OVN contributing guidelines. GitHub PRs are not the review path for this project. The OpenShift-side change for OCPBUGS-114016 is openshift/ovn-kubernetes#3424 |
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Summary
Locally generated IGMP/MLD membership queries were injected into
OFTABLE_LOCAL_OUTPUTwith outport set toMC_FLOOD. That floods the query to every local port, including patch ports towards logical routers.In scaled topologies (many VIFs and/or many connected routers, e.g. OpenShift UDN gateway routers) the nested resubmits exceed OVS's 4096 resubmit limit.
ovs-vswitchdthen drops the packet-out:Snooped queries are already re-injected with
MC_FLOOD_L2viaip_mcast_forward_query(). This change uses the same key for locally generated querier queries so they stay in the L2 broadcast domain (RFC 4541) and skip router ports that would drop the traffic anyway.This is the remaining IGMP path after ARP/GARP fan-out was reduced; those packets still used
MC_FLOODand skipped northd'seth.mcast && ip→_MC_flood_l2split.Test plan
IGMP snoop/querier/relayand MLD querier tests updated to assert queries reach the local switch VIFs and do not appear on other switches' portsmake check(IGMP/MLD querier tests)Reported-at: https://issues.redhat.com/browse/OCPBUGS-114016
Signed-off-by: Trushna Deokar tdeokar@redhat.com