Public bug reported:
OVN 24.03.9 stops refreshing (ARP/ND) the MAC bindings for
learned neighbors that are not covered by any of the logical router port's
configured prefixes, e.g. /32 addressing with a reachable default gateway,
even when an explicit Logical_Router_Static_Route.output_port route selects
that port and traffic is still forwarded successfully.
This is a regression introduced by the 24.03 backport of upstream commit
05005d6e78db ("mac-cache: Make sure we re-arp for proper IP for LRP with
multiple IPs."), cherry-picked to branch-24.03 as ed55f701.
In mac_binding_probe_stats_run() (controller/mac-cache.c), when no LRP prefix
contains the neighbor, the probe source address is left as in6addr_any and the
subsequent guard suppresses the ARP/ND refresh probe. Routing still supports
the next hop: find_static_route_outport() already falls back to the port's
first address for this case. The result is that, with
options:mac_binding_age_threshold enabled, the MAC bindings for off-subnet
next hops are silently left to age out instead of being refreshed.
Reported upstream:
[OVN] 24.03.9 regression: no MAC-binding refresh probes for off-subnet
next hops ([email protected], 2026-10-29), with a native testsuite
reproducer (mac-binding-off-subnet).
Proposed fix:
Fall back to the port's first address when no prefix contains the neighbor,
matching find_static_route_outport(), while preserving the matching-subnet
selection introduced by the original fix.
** Affects: ovn (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2172542
Title:
ovn 24.03.9 regression: no MAC-binding refresh probes for off-subnet
next hops
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