ISIS/6/ADD_L1_SUMRT_FAIL:ISIS [process-id] failed to add the Level-1 summary route. (MTID=[USHORT])
IS-IS failed to add a summarized Level-1 route.
[process-id]
Indicates the ID of an IS-IS process.
MTID
Indicates the ID of a topology.
Failed to add a summarized Level-1 route.