Lesson 4 - Routers

   Introduction

A router operates at the Network Layer of the OSI reference model, distinguishing between Network Layer protocols and making intelligent packet-forwarding decisions based on each packet's network address. As Network Layer devices, routers are protocol-dependent. They can interconnect networks that have the same network communication architecture, but possibly different lower level architectures. In contrast, Layer 2 devices (bridges and switches) are considered protocol-independent, because they can connect networks that use different Layer 3 protocols.

   Objectives

At the end of this lesson you will be able to:

1.	Explain how routers work
2.	Describe how a router is different from a bridge or a switch
3.	Explain the difference between a collision domain and a broadcast domain
4.	Name the key advantages and disadvantages of routers

Key Point
Routers use packet addresses to route information between networks.

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