Advantages

Border routing can be advantageous in some situations:

In networks with many routers, border routers can limit the spread of routing-related information, resulting in increased network stability.
When routing messages between separate enterprises—for example, to a business partner outside your intranet—border routers can isolate intranet topology information.
Border router policies enforce subject gating restrictions pairwise between routing table entries (that is, neighbors and local networks). You can specify a separate policy for each ordered pair.