Cisco IOS Access Lists

Generic route map format

To create generic policies for routing, we need two things: a way to identify routes to be affected by a policy and a way to set policies once those routes have been identified. Route maps are a series of entries that have exactly those two sets of elements. The name “route map” is entirely appropriate: routes are identified and mapped to a policy setting.

Each route map entry has the following format:

route-map route-map-name {permit|deny} {sequence number}
match clauses 
policy settings

The sequence number determines the sequence in which route maps are evaluated. Entries with lower sequence numbers are evaluated before blocks with higher sequence numbers with the same route map name. Match clauses are policy set definitions, usually some kind of access list reference intended to match route characteristics. There can be multiple match clauses, and a route has to match all of the clauses in order to match the entry. permit and deny are the two possible keywords for route map entries. A permit says that a route with the match clause characteristics will have the policy settings applied to it. A deny says that a route that matches a match clause will no longer be evaluated by the route map, and further comparisons to other route map entries will stop. No route attributes are changed when a deny is encountered.

Here is an example of a route map:

route-map ROUTES-IN permit 10 match ip address 5 6 set local-preference 110 route-map ROUTES-IN deny 20 match ...