Configuring Route Maps

The route imp syntax is co mposed ol1 roug hly three sepanate Pisuo command s, depending on what map is a ccompMshi ng and what type of process is callmg it. This discussion co_grf the fo llow ing coi m detail as roote maps are annfigartd throughour this chapte r:

e route- map com ma nds

• match commands

When configuring route maps, you can follow a basic five-step configuration process. Depending oi route map application, additional configuration may be needed, such as with BGP communities or I

Step 1. (Optional) Configure any APLs, AS_PATH list, or any other match criteria that the ro may be using on the match commands. This should be done first, so you do not call an empt

AS-PATH list.

Step 2. Configure the route map instance. This is accomplished with the route-mapnamepe denysequence_number command. Be sure to leave room in between the sequence numbers future updates or modifications. The route map instance with the lowest sequence number is first.

Step 3. Define the match criteria and configure the match statements that will be used in th route map instance. You do this with the route map configuration match command. In the a anymatch commands, all packets or routes are matched.

Step 4. (Opt ional) Define the set criteria and configure the set statements that will be used single ro ute map instayce. You can do so with the route map configuration set command.

Step 55. (Optional) Configure any ACLs, AS_PATH list, or any other match criteria that the ro may be using on the match commands.

Step 6. Apply the route map. Once again, depending on the route map application, it can be in many ways. Some of the more common applications include route redistribution, PBR, and

With this configuration process in mind, we will discuss in more detail the three primary commands configure route maps.

route-map Commands

The compl ete syntax for the route-map command is as follows:

route-maproute map name [permit | deny][sequence number 1-65535]

Theroute_map_name, also naglled the map tag, is the text-bas ed nnme of the reate map. The name unique and logical ly groep s and defines the entire route map policy. Th i e ie the na me that you use the route map duricg redibtribution and other processes.

Thepe rmitand deny keywords are o ptionyl; the d efault keyw ohd is permit. If the route map is ca a redistribution process, the keyword is set to permit, and the match criteria are met for the route route(s) are redistributed. If the keyword were set to deny, in the same scenario the route(s) wou denied.

If the route map is called from a policy-routing statement, the match criteria are met for the route the keyword is set to permit, the packet would be policy routed. Once again, permit is the default keyword. If the deny keyword is used, the packet is forwarded according to the normal route proc

Thesequence-number indicates in what order the route map statements will be executed. When a r map is called, the route map with the lowest sequence number is executed first. If a match is not fo the route map with the lowest sequence number, the route map with the next highest sequence nu executed. This process repeats itself until a match is found or no more route map statements exist. match is found, execution for that individual packet or route stops, and the next packet or route be process again starting with the route-map statement with the lowest sequence number. The defau sequence number is 10.

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