Lab 4 Introduction

The purpose of this lab is to gain familiarity and experience with routers and routing protocols that operate within a single network (administrative domain). Routers within an administrative domain are used to transmit packets between local area networks that are geographically separated. Intra-domain routing takes place at layer 3 of the network protocol stack, and is used to establish forwarding tables for routers that all belong to one network. These activities are distinct (although related) from the protocols used to establish routes between network or inter-domain routing, which is the topic of Lab #5.

There several different intra-domain routing protocols that are used, but the Open Shortest Path First (OSPF) protocols is most widely used. OSPF is based on Dijkstra's distributed routing algorithm which uses link state to establish the lowest cost paths between nodes in a network. Optimal (lowest cost) routes are established after nodes in a domain receive special, link state packets from all other nodes. This distributed routing algorithm enables a network to establish and maintain paths in the face of link outages and other changes of conditions.

Students will be introduced to the basic concepts of intra-domain forwarding and routing in this lab by configuring and running tests a small network composed of IP routers. Expertise with inter-domain routing configuration is important if you are interested in eventually getting a job as a network administrator. The routers used in this lab are not emulated systems - they are Cisco routers running real link state routing protocols commonly used in networks today. Students will be introduced to the command line interface of Cisco's Internetwork Operating System (IOS), which is similar to the operating systems and command line interfaces found on many network devices. As its name implies, IOS is the operating system that controls the behavior of the interfaces on the router.

This lab will be conducted entirely via Schooner. This lab will be about the same level of complexity as Lab #2 so please start early. Lab #4 will be the only lab in which inter-domain routing is covered, so if you would like to experiment with inter-domain routing in other ways, please see Prof. Barford for ideas.

Objectives