Designing Static Route Propagation in a Service Provider Network

This topic identifies the design considerations for propagating static routes in a service provider network.

You can easily extend the principle of using tags when you are configuring static routes, and of assigning different communities based on those tags, to implement a more complex routing policy. To propagate static routes in a service provider network, complete these steps:

Step 1 Identify all different service levels that are offered to customers and then all the different combinations of these service levels.

Step 2 Assign each combination its own tag value and its own community.

Step 3 Configure a route-map, which selects routes with each of the assigned tags and sets the corresponding community value. Because the processing of a route-map stops when the match clause of a statement is met, each route should be assigned a single combination of communities only. Therefore, you must take great care to assign a tag and a community combination to each combination of services that are provided.

Note When the provider edge routers redistribute static routes into BGP, these routes must pass through the route-map. BGP assigns the correct community depending on the tag values that are given on the configuration line for each of the static routes.

Step 4 Finally, configure static routes. Before you configure a static route for a specific customer, you must identify the combination of the services that are provided to this customer. Then you must look up the corresponding tag value. After you have configured the route, you must assign the tag.

With this routing policy, every static route to a customer network is assigned a tag and the redistributed BGP route is assigned a corresponding community. The BGP communities that are attached to the routes signal to other routers in the ISP network which particular service combination you should use.

5-28 Configuring BGP on Cisco Routers (BGP) v3.2 © 2005, Cisco Systems, Inc.

Example: Static Route Propagation

This example shows a scenario with varied service levels in which static route propagation is configured in a BGP environment.

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