ISL is out-of-sync

Solution 1
Cause

Mismatch with the ISL version or switch platform or both.

Action
  1. Run the show vsx status command.

    In the following example, the ISL channel is shown as in-sync; however, if the ISL channel was not in-sync, a different status would be provided.

    switch# show vsx status
    VSX Operational State
    ---------------------
      ISL channel             : In-Sync
      ISL mgmt channel        : operational
      Config Sync Status      : in-sync
      NAE                     : peer_unreachable
      HTTPS Server            : peer_unreachable
    
    Attribute           Local                       Peer
    ------------        --------                    --------
    ISL link            1/1/43                      1/1/43
    ISL version         2                           2
    System MAC          48:0f:cf:af:70:84           48:0f:cf:af:c2:84
    Platform            8320                        8320
    Software Version    10.03.0001                  10.03.0001
    Device Role         primary                     secondary
  2. If there is an ISL version mismatch, update the software so the ISL version is the same on the local and peer VSX switch.
  3. If the switches have mismatching platforms, create an ISL link that connects two VSX switches with the same platform.
Solution 2
Cause

The role is not configured on any of the VSX switches or the same role is configured on both VSX switches.

Action
  1. Run the show vsx status command.

    If the roles are set incorrectly, the command displays the role inconsistent status.

  2. Set the roles correctly so that one of the VSX switches has the primary role and the other switch has the secondary role. To set a switch role, enter the role {primary | secondary} command.
Solution 3
Cause

The ISL interface is down on any one switch in the VSX pair.

Action
  1. Check ISL state and ISL link status by entering: switch# show vsx status inter-switch-link

    In the following example, the ISL state and link status are shown as in-sync and up; however, if the ISL interface is down, a different status would be provided.

    switch# show vsx status inter-switch-link
    State                     : In-Sync
    Link Status               : up
    Mgmt state                : operational
    
    Inter-switch link Statistics
    ----------------------------
    Hello Packets Tx          : 4572
    Hello Packets Rx          : 4573
    Data Packets Tx           : 80634
    Data Packets Rx           : 80637
    Mgmt Packets Tx           : 25946
    Mgmt Packets Rx           : 25167
    Mgmt Packet Drops         : 0
  2. Re-enable the ISL interface by going to that interface context and entering no shutdown:
    switch(config)# interface 1/1/1
    switch(config-if)# no shutdown