IP Routing Fundamentals

Dissimilar Architectures

The actual need for supporting two or more routing protocols in an internetwork can come from a variety of sources. Generally speaking, the need derives from architectural dissimilarities between networks that must be internetworked. These dissimilarities can be a result of network administrators' preferences. One network's administrator may prefer Open Shortest Path First (OSPF) and a mixed-vendor environment, for example, whereas the other administrator operates a Cisco-only network and runs Enhanced Interior Gateway Routing Protocol (EIGRP).

Alternatively, dissimilar network architectures could indicate a functional distinction within a network, such as interior and exterior gateway functions. Some of the more common ...