Summary

This chapter began by discussing the difference between routed and routing protocols, and then reviewed the design implications of different routing protocols. We discussed the differences between distance-vector and link-state protocols and explored several protocols in depth, including RIP, IGRP, and Enhanced IGRP.

RIP is a distance-vector routing algorithm that only uses hop count to find the best path to a remote network. It uses broadcasts for route updates, and no formal neighbor relationships are established, so it is often referred to as “routing by rumor.”

IGRP is also a distance-vector routing algorithm. IGRP uses bandwidth and delay of the line to determine the best path to an internetwork. It can also be configured to use MTU, load, and reliability.

EIGRP is an enhanced version of IGRP. It uses both distance-vector algorithms and link-state properties to build an internetwork route table with support for IP, IPX, and AppleTalk. It establishes formal neighbor relationships and maintains both topology and route tables.