Exchanging Protocols

With the introduction of classless routing, it was not possible for classful routing protocols such as RIP and IGRP to understand entire routing tables. In some cases, routing packets to destinations within the same major network is no longer possible. Therefore, it may become necessary to exchange one protocol for another.

Take, for example, the case of the Internet making use of class A networks between multiple customers. As discussed in Chapter 6, “Routing Information Protocol,” RIPV1 will not accept routes across a different major network for its own connected network, and therefore will not route packets to that destination.

Now, consider the network shown in Figure 12-1: Y.com. The Y.com network owns part of the ...

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