IS-IS administrative tags enable a network administrator to configure route tags to tag IS-IS route prefixes. These tags can subsequently be used to control IS-IS route redistribution or route leaking.
IS-IS route tagging can be applied to IP addresses of an interface and to administrative policies with a route map. A network administrator can tag a summary route and then use a route policy to match the tag with one or more attributes for the route.
Using these administrative policies, the operator can control how a router handles route exchanges with its IS-IS neighboring routers. Administrative policies are also used to govern the installation of routes in the routing table.
Route tags allow policies to do the following:
redistribute routes received from other protocols in the routing table to IS-IS
redistribute routes or SRv6 locators between levels in an IS-IS routing hierarchy
summarize routes redistributed into IS-IS or within IS-IS by creating aggregate (summary) addresses