Fix IPv6 gateway reachability with ND proxy#873
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IPv6 gateway traffic (DHCPv6/ICMPv6) fails when VPP takes over the uplink. - Without gateway ND proxy, host NS for the default gateway is dropped by VPP with "neighbor solicitations for unknown targets" error due to missing /128 target entry in the tap FIB. Fix: - Enable ND proxy for the gateway on the tap so that the host can resolve the gateway via VPP. This requires VPP patch https://gerrit.fd.io/r/c/vpp/+/44350 to fix unicast NA handling in ND proxy which was leading to a NA loop bug. Signed-off-by: Aritra Basu <aritrbas@cisco.com>
hedibouattour
approved these changes
Feb 5, 2026
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Problem
IPv6 gateway traffic (DHCPv6/ICMPv6) fails after VPP takes over the host’s uplink interface.
RCA:
Without gateway ND proxy, host Neighbor Solicitation (NS) for the infrastructure gateway is dropped by VPP with
neighbor solicitations for unknown targetserror due to missing /128 target entry in the tap FIB.Fix:
Enable ND proxy for the gateway on the tap so that the host can resolve the gateway via VPP.
This requires VPP patch https://gerrit.fd.io/r/c/vpp/+/44350 to fix unicast NA handling in ND proxy.
When a unicast Neighbor Advertisement (NA) was received for a proxied address, VPP generated another NA on the same interface, causing a potential NA loop bug. This has been fixed in the given patch.