TABLE OF CONTENTS You might think that one routing protocol is more than enough for your network, but some administrators find themselves in a situation where they have to implement more than one routing protocol in a network. This often occurs when BGP is needed, when proprietary routing protocols are used such as EIGRP, when legacy routing support must be enabled, or when organizations using different routing protocols merge. By default, different routing protocols do not share their routing information with each other, even in the same VR. This is because they do not understand each other, and also because the metrics are often incompatible. If full connectivity is needed across the network, the routes from one protocol must be redistributed into another routing protocol so they can be advertised by the other protocol.
In this section, we will cover how route redistribution works, and how it enables you to handle multiple routing protocols in a network. We will give examples of how redistribution can be performed between different protocols, and some best practices to help strengthen your knowledge of multiprotocol routing.
Route redistribution essentially works by pulling routes out of the routing table from one protocol, and then advertising them out another protocol. The Juniper firewalls use route maps to select which routes and which protocols to pull from the routing table, as well as which routes to advertise. As mentioned earlier in this chapter, route maps can match routes both by the route...
