Troubleshoot IPv6 Connectivity Loss

If the switch experiences loss of IPv6 connectivity, use the following procedure to troubleshoot the issue.

Procedure

  1. Enter Global Configuration mode:

    enable

    configure terminal

  2. Through the command line interface, make sure the required routes are in place and the corresponding neighbor entries are resolved (that is, in REACHABLE, PROBE, DELAY or STALE state).
  3. INCOMPLETE neighbor state indicates a problem if the corresponding neighbor is used by some of the IPv6 routes. This applies to neighbor entries with link-local addresses.
    Note

    Note

    Global addresses are not normally used as next hops. Having a global IPv6 neighbor entry as INCOMPLETE does not usually lead to a connectivity issue.

  4. If the corresponding route is not in place then this is a routing issue. If the neighbor is not present or is INCOMPLETE, then further debugging is needed on the network level (that is, the state of other nodes needs to be examined).
  5. Disabling and re-enabling IPv6 on the VLAN often recovers connectivity.
  6. Display the RSMLT and MLT status:

    show ip rsmlt

    show mlt

    Make sure the RSMLT peer MAC is learned and the IST state is ist.