306 C HAPTER 11: INTERNET P ROTOCOL (IP)Setting Up RIPRouting PoliciesTo configure a routing policy, follow these general steps:1 Establish an Export policy that controls the advertisement of routesthrough RIP, regardless of the source from which the route is learned.2 Establish an Import policy that accepts or refuses to accept informationon routes learned by RIP from a trusted neighbor.3 To control the reporting of routes that are learned from specific sources,establish the following policies:n Export policy for routes learned from OSPFn Static policy for reporting static (user-configured) routesIf you decide to have routes reported with a metric that is calculated fromthe routing table, you can manipulate the conversion formula that RIPuses to convert a routing table metric into one that RIP understands.4 Establish a policy to report OSPF routes so that the metrics that arereported with these routes are imported into RIP without being changed.Effects and ConsequencesConsider these points when you use routing policies:n Configure the administrative weight setting carefully because thissetting has the highest priority in resolving policy conflicts.n If you use routing policies, do not implement static routes. Routingpolicies work with routes that are updated dynamically.n Use routing policies only if you need the security, or if you need morecontrol over the routing tables than other IP features, such as VLSMs,give you.n To control whether a route is accepted or forwarded without makingspecific changes to your network configuration, consider setting theCost metric as high as possible, and the administrative weight as lowas possible.
