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CCNA Certification All-In-One For Dummies by Silviu Angelescu

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Chapter 5: Enhanced Interior Gateway Routing Protocol (EIGRP)

Exam Objectives

Describing the features and characteristics of EIGRP

Distinguishing EIGRP from IGRP

Describing EIGRP routing decision criteria

Describing EIGRP route updates and convergence

Describing EIGRP routing tables and operation

Understanding the Diffusing Update Algorithm (DUAL)

Deploying EIGRP

Verifying and troubleshooting EIGRP on a Cisco router

As the name implies, the Cisco-proprietary Enhanced Interior Gateway Routing Protocol (EIGRP) is an interior gateway protocol that contains many advantages over Routing Information Protocol (RIP) and its superseded predecessor, the Interior Gateway Routing Protocol (IGRP). EIGRP is the enhanced version of IGRP. Like RIP, IGRP is known as a distance vector protocol, but it uses a dramatically improved distance vector algorithm to determine the best path to a particular destination. IGRP relies more heavily on the bandwidth and delay metrics of a route as opposed to RIP, which relies on the distance of a route.

EIGRP includes features commonly found in more advanced link-state protocols. EIGRP also uses a more advanced method of loop mitigation than both RIP and IGRP, providing a 100-percent loop-free environment.

Other benefits of EIGRP include high scalability with minimal network overhead and very fast convergence speeds. To fully understand the capabilities of EIGRP, it is beneficial to first take a look at the protocol on which it is based, namely IGRP.

IGRP — ...

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