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IPv6 traffic from some hosts stops passing randomly through the Security Gateway / Active ClusterXL member running Gaia OS
Symptoms
  • IPv6 traffic from some hosts stops passing randomly through the Security Gateway / Active ClusterXL member running Gaia OS.

  • Each time this happens to different hosts on the network.

  • In ClusterXL, performing a failover to the Standby cluster member resolves the issue immediately until the next time the issue happens on the newly Active cluster member.

  • Issue might resolve itself after some time.
  • 'kernel: neighbor table overflow' message appears repeatedly in /var/log/messages files.
  • while adding IPv6 neighbor manually following error is observed: "RTNETLINK answers: No buffer space available"
Cause

Missing IPv6 neighbor. After reaching a certain threshold amount of IPv6 neighbors, Gaia OS cannot add more to its neighbor table. If those clients will send a ND solicitation to Gaia OS, then the Gaia OS will not respond with ND solicitation advertise, due to not having a neighbor in the table (if it also does not have them in the cache, which will happen some time afterwards).


Solution
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