Why there is difference of time to hold the neighbour table entries in cache for IPv4 versus IPv6 ?

Solution Verified - Updated -


  • RHEL behaves differently for IPv4 vs IPv6 when it comes to storing neigh table entries in cache.
  • When there are more than one ARP reply for an IPv4 address, details in first reply gets stored in neighbour cache and is used by the system for further communication but in case of IPv6 the last Neighbor Advertisement gets stored in cache and is used by system. Why there is such a difference ?


  • Red Hat Enterprise Linux 6 (All minor versions)
  • Neighbour table cache (# ip neigh show)
  • IPv6

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