Configuring Routing Policy

The system supports a number of features that allow the service provider to control the exchange of routing information between virtual routers in the system, between routers in the network, and between protocols within a router:

• Access lists - Provide filters that can be applied to route maps or distribution lists. They allow policies to be created, such as a policy to prevent forwarding of specified routes between the BGP-4 and IS-IS routing tables.
• Route maps - Modify the characteristics of a route (generally to set its metric or to specify additional attributes) as it is transmitted or accepted by a router. Route maps may use access lists to identify the set of routes to modify.
• Distribution lists - Control the routing information that is accepted or transmitted to peer routers. Distribution lists always use access lists to identify routes for distribution. For example, distribution lists could use access lists to specify routes to advertise.
• Redistribute routes - Allow routes to be shared between routing protocols and routing domains. For example, a subset of BGP-4 routes could be leaked into the IS-IS routing tables.

See ERX Routing Protocols Configuration Guide, Vol. 1, Chapter 1, Configuring Routing Policy, for details.