Configure a system ID. You must configure a system ID before you enable IS-IS. You cannot delete the system ID but you can change it if you first disable IS-IS.
default system-id
no system-id
system-id xxxx.xxxx.xxxx - 6 bytes
system-id xxxx.xxxx.xxxx - 6 bytes
The default system ID is the node Backbone MAC.
IS-IS Router Configuration