Chapter 11 Configuring and Testing Your Network

This chapter studies the process for connecting and configuring computer, switch, and routers into an Ethernet LAN. This will introduce also the basic configuration for Cisco network devices and is require the use of the Cisco Internetwork Operating System (IOS) and the related configuration files for intermediary devices. It is used for routers, LAN switches, small Wireless Access Points, large routers with dozens of interfaces, and many other devices. The services provided by the Cisco IOS are generally accessed using a command line interface (CLI).

The Cisco IOS is designed as a modal operating system. The term modal describes a system where there are different modes of operation, each having its own domain of operation. The CLI uses a hierarchical structure for the modes. The major modes are: User executive mode, Privileged executive mode, Global configuration mode, other specific configuration modes. Each mode is used to accomplish particular tasks and has a specific set of commands that are available when in that mode. The two primary modes of operation are: User EXEC, Privileged EXEC. The user EXEC mode is at the top of the modal hierarchical structure. This mode is the first entrance into the CLI of an IOS router. The privileged EXEC mode can be identified by the prompt ending with the # symbol.

Switch#

In order to access the privileged EXEC mode, use the enable command. The privileged EXEC mode is sometimes called the enable mode.

The syntax for entering the enable command is:

Router>enable

Configuring Router Ethernet Interfaces

Router Ethernet interfaces are used as the gateways for the end devices on the LANs directly connected to the router.

Each Ethernet interface must have an IP address and subnet mask to route IP packets.

To configure an Ethernet interface follow these steps:

1. Enter global configuration mode.

2. Enter interface configuration mode.

3. Specify the interface address and subnet mask.

4. Enable the interface.

Configuring Router Serial Interfaces

Serial interfaces are used to connect WANs to routers at a remote site or ISP.

To configure a serial interface follow these steps:

1. Enter global configuration mode.

2. Enter interface mode.

3. Specify the interface address and subnet mask.

4. Set the clock rate if a DCE cable is connected. Skip this step if a DTE cable is connected.

5. Turn on the interface.