ABSTRACT
Experimenting is an important step in acquiring effective skills in computer networking. This chapter presents the main features of GNS3, Cisco Internetwork Operating System (IOS), and Wireshark, and explains the basic router configurations. Configuring a routing protocol in Cisco IOS always involves creating a routing process. The network devices can be drag-and-dropped from the left pane, where they are organized in categories. One way to determine if a network has converged in Link State Routing experiments is to observe the control packets transmitted by the routers, e.g. using Wireshark. GNS3 is a network emulator that allows testing network configurations using the actual operating system of networking equipment and using Wireshark for packet analysis. Wireshark is a protocol analysis tool. It can capture all packets that cross a network interface and decode their complete contents, e.g. it identifies the protocols of the various layers and the source and destination addresses.
