IS-IS route tags are configurable in the following ways:
setting a route tag for an IS-IS interface
setting a route tag on an IS-IS passive interface
setting a route tag for a route redistributed from another protocol to IS-IS
setting a route tag for a route redistributed from one IS-IS level to another IS-IS level
setting a route tag for an IS-IS default route
setting a route tag for an IS-IS summary address