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Cisco ICND2 Foundation Learning Guide: Implementing an EIGRP Solution

Chapter Description

To assist in your studies for the ICND2 exam, this chapter reviews the basics of dynamic routing and examines the operation, configuration, and troubleshooting of EIGRP for IPv4 and IPv6.

Chapter Summary

Dynamic routing protocols are defined by type, distance vector or link state. Distance vector protocols use a metric to determine the path through the network on a hop-by-hop basis. Link-state protocols keep a topology of all routers and links in the network. Examples of distance vector protocols are EIGRP and RIP. Examples of link-state protocols are OSPF and BGP.

Dynamic routing protocols are classified as Exterior Gateway Protocol (EGP) or Interior Gateway Protocol (IGP). An EGP is used between different autonomous systems, such as autonomous systems connected to the public Internet. IGPs are used inside a network. The only current EGP for IPv4 and IPV6 is BGP. Examples of IGPs are OSPF, EIGRP, and RIP.

EIGRP is an IGP that is considered an advanced distance vector protocol because it has many added features, such as partial updates. EIGRP uses the DUAL algorithm for its topology and metric calculations. It is suitable for many network designs. It supports multiple protocols through separate processes, called protocol-dependent modules.

EIGRP for IPv4 and EIGRP for IPv6 have very similar operating models, such as configuration and troubleshooting. The main deviations are where IPv4 and IPv6 differ as protocols. The primary differences are that IPv6 uses link-local addressing for EIGRP (IPv6) neighbor establishment; EIGRP for IPv6 is configured on an interface-by-interface basis; and the creation of passive interfaces in IPV6 is done not by configuring an interface but by adding configuration for the passive interface.

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