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 Intermediate System-to-Intermediate System (IS-IS) route redistribution or route leaking.
The IS-IS support for route tags allows the tagging of IP addresses of an interface and use the tag to apply administrative policy with a route map. A network administrator can also tag a summary route and then use a route policy to match the tag and set one or more attributes for the route.
Using these administrative policies allow the operator to control how a router handles the routes it receives from and sends to 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 redistribute routes received from other protocols in the routing table to IS-IS
policies to redistribute routes between levels in an IS-IS routing hierarchy
policies to summarize routes redistributed into IS-IS or within IS-IS by creating aggregate (summary) addresses