This is tracking the upstream effort needed to deliver the solution to the bug described below.

 Problem Description: Clearly explain the issue.

When using Distributed Gateway Port and HA, IPv6 ND_NA packet
received on the router port causes all HA chassis to try updating the
Mac_Binding table, often causing transaction errors.

Reception of ARP packets do not cause the same issue.

 Impact Assessment: Describe the severity and impact (e.g., network down,availability of a workaround, etc.).

Transaction errors causes full recomputes, hence high CPU utilization.

 Software Versions: Specify the exact versions in use (e.g.,openvswitch3.1-3.1.0-147.el8fdp).

Reproduced on main.

  Issue Type: Indicate whether this is a new issue or a regression (if a regression, state the last known working version).

Not a regression.

 Reproducibility: Confirm if the issue can be reproduced consistently. If not, describe how often it occurs.

Not all ND_NA received on the router ports cause a transaction error (thanks to MAX_MAC_BINDING_DELAY_MSEC). 

However, sending 50 ND_NA packets to 3 HA chassis I see the problems most of the times.

 Reproduction Steps: Provide detailed steps or scripts to replicate the issue.

Send many ND_NA from outside to the router.

 Expected Behavior: Describe what should happen under normal circumstances.

Only the active HA chassis should update sb, hence no transaction errors.

 Observed Behavior: Explain what actually happens.

Reception of ND_NA packets causes all HA chassis to try to update the same mac_binding in sb, hence increasing the risk of transaction failures.

 Troubleshooting Actions: Outline the steps taken to diagnose or resolve the issue so far.

 Logs: If you collected logs please provide them (e.g. sos report, /var/log/openvswitch/* , testpmd console)