Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.112.0P1 - Page 124

Route Maps Although route maps are similar to ACLs and prefix lists in that they consist of a series of commands that contain a matching criterion and an action, route maps can modify parameters in matching packets. Implementation Information ACLs and prefix lists can only drop or forward the packet or traffic. Route maps process routes for route redistribution. For example, a route map can be called to filter only specific routes and to add a metric. Route maps also have an "implicit deny." Unlike ACLs and prefix lists; however, where the packet or traffic is dropped, in route maps, if a route does not match any of the route map conditions, the route is not redistributed. The implementation of route maps allows route maps with the no match or no set commands. When there is no match command, all traffic matches the route map and the set command applies. Important Points to Remember • For route-maps with more than one match clause: • Two or more match clauses within the same route-map sequence have the same match commands (though the values are different), matching a packet against these clauses is a logical OR operation. • Two or more match clauses within the same route-map sequence have different match commands, matching a packet against these clauses is a logical AND operation. • If no match is found in a route-map sequence, the process moves to the next route-map sequence until a match is found, or there are no more sequences. • When a match is found, the packet is forwarded and no more route-map sequences are processed. • If a continue clause is included in the route-map sequence, the next or a specified route-map sequence is processed after a match is found. Configuration Task List for Route Maps Configure route maps in ROUTE-MAP mode and apply the maps in various commands in ROUTER RIP and ROUTER OSPF modes. The following list includes the configuration tasks for route maps, as described in the following sections. • Create a route map (mandatory) • Configure route map filters (optional) • Configure a route map for route redistribution (optional) • Configure a route map for route tagging (optional) Creating a Route Map Route maps, ACLs, and prefix lists are similar in composition because all three contain filters, but route map filters do not contain the permit and deny actions found in ACLs and prefix lists. Route map filters match certain routes and set or specific values. To create a route map, use the following command. • Create a route map and assign it a unique name. The optional permit and deny keywords are the actions of the route map. CONFIGURATION mode 124 Access Control Lists (ACLs)