EIGRP is one of the few routing protocols that can work with multiple routed protocols. Cisco implements what it calls protocol-dependent modules in the code that handle protocol-specific tasks. For example, IPX EIGRP needs to send and receive SAP updates. IP and IPX form neighbors using different message formats.
EIGRP operates the same way for all routed protocols—that is, it uses DUAL to find the shortest path to forward data toward. Another task of protocol-dependent modules is to pass data into the DUAL process so that a proper topology table, and eventually a route table, can be formed.
Like IGRP, EIGRP deploys the concepts of split horizon and poison reverse to prevent routing loops.
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