Table Of Contents

Before You Begin

Preparing to Configure the Layer 3 Switch Routers

Understanding the Command-Line Interface

Understanding Cisco IOS Command Modes

Using the Command Modes

Getting Help

More Configuration Documentation

Before You Begin

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This chapter gives you a process to follow in configuring the Layer 3 switch routers, lists the information you need to have before you begin, and describes Cisco IOS command modes.

This chapter contains the following sections:

•Preparing to Configure the Layer 3 Switch Routers

•Understanding the Command-Line Interface

•Understanding Cisco IOS Command Modes

•More Configuration Documentation

Preparing to Configure the Layer 3 Switch Routers

Before configuring your switch router, have the following information available:

•A map of your network topology

•The network protocol(s) you are supporting (IP or IPX)

•The routing protocol you will use for each network protocol

•The IP or IPX addresses and the IP subnet masks for each network interface

•The IP addressing plan for each network protocol

Follow these steps to configure Layer 3 switch routers.

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Step 1 Set up the hardware as described in either the Catalyst 2948G-L3 Hardware Installation Guide or the Catalyst 4908G-L3 Hardware Installation Guide.

Step 2 Perform initial configuration tasks; see "Configurations for the Layer 3 Switch Router."

Step 3 Configure the interfaces; see "Configuring Interfaces."

Step 4 Configure VLAN encapsulation; see "Configuring VLAN Encapsulation."

Step 5 Configure networking and routing protocols; see "Configuring Networking Protocols."

Step 6 Configure bridging; see "Configuring Bridging."

Step 7 Configure EtherChannel; see "Configuring EtherChannel."

Step 8 Configure optional QoS and SDM functionality; see "Configuring Quality of Service" and "Configuring the Switching Database Manager."

Step 9 Perform optional system management and performance tasks; refer to the Cisco IOS Command Reference release12.0 publication.

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Understanding the Command-Line Interface

You can configure the switch router from the command-line interface (CLI), the user interface, and prompt on the router console or terminal, or by using remote access.

To use the CLI, your terminal must be connected to the switch router through the console port. By default, the terminal has a basic configuration, which should work for most terminal sessions.

Understanding Cisco IOS Command Modes

The Cisco IOS user interface has several different modes. The commands available to you depend on which mode you are in. To get a list of the commands available in a given mode, type a question mark (?) at the system prompt.

Table 2-1 describes the most commonly used modes, how to enter the modes, and the resulting system prompts. The system prompt helps you identify which mode you are in and, therefore, which commands are available to you.

Table 2-1 Frequently Used IOS Command Modes 

Mode	What You Use It For	How to Access	Prompt
User EXEC	Connect to remote devices, change terminal settings on a temporary basis, perform basic tests, and display system information.	Log in.	Router>
Privileged EXEC (also called Enable mode)	Set operating parameters. The privileged command set includes the commands in user EXEC mode, as well as the configure command. Use this command mode to access the other command modes.	From user EXEC mode, enter the enable command and the enable password.	Router#
Global configuration	Configure features that affect the system as a whole.	From privileged EXEC mode, enter the configure terminal command.	Router(config)#
Interface configuration	Enable features for a particular interface. Interface commands enable or modify the operation of a Fast Ethernet or Gigabit Ethernet port.	From global configuration mode, enter the interface type number command. For example, enter interface fastethernet 1 for Fast Ethernet or interface gigabitethernet 49 for Gigabit Ethernet interfaces.	Router(config-if)#
Line configuration	Configure the console port or VTY line from the directly connected console or the virtual terminal used with Telnet.	From global configuration mode, enter the line console 0 command to configure the console port or the line vty line-number command to configure a VTY line.	Router(config-line)#

When you start a session on the switch router, you begin in user EXEC mode. Only a small subset of the commands are available in user EXEC mode. To have access to all commands, you must enter privileged EXEC mode, also called Enable mode. Normally, you must type in a password to access privileged EXEC mode. From privileged mode, you can type in any EXEC command or access global configuration mode. Most of the EXEC commands are single-use commands, such as show commands, which show the current configuration status, and clear commands, which clear counters or interfaces. The EXEC commands are not saved across reboots of the Layer 3 switch router.

The configuration modes allow you to make changes to the running configuration. If you later save the configuration, these commands are stored across Layer 3 switch router reboots. You must start in global configuration mode. From global configuration mode, you can enter interface configuration mode, subinterface configuration mode, and a variety of protocol-specific modes.

Read-only memory (ROM) monitor mode is a separate mode used when the Layer 3 switch router cannot boot properly. For example, your Layer 3 switch router or access server might enter ROM monitor mode if it does not find a valid system image when it is booting, or if its configuration file is corrupted at startup.

Using the Command Modes

The Cisco IOS command interpreter, called the EXEC, interprets and executes the commands you enter. You can abbreviate commands and keywords by entering just enough characters to make the command unique from other commands. For example, you can abbreviate the show command to sh and the configure terminal command to config t.

When you type exit, the switch router backs out one level. In general, typing exit returns you to global configuration mode. Enter end to exit configuration mode completely and return to privileged EXEC mode.

Getting Help

In any command mode, you can get a list of available commands by entering a question mark (?).

Router> ?

To obtain a list of commands that begin with a particular character sequence, type in those characters followed immediately by the question mark (?). Do not include a space. This form of help is called word help, because it completes a word for you.

Router# co?

configure

To list keywords or arguments, enter a question mark in place of a keyword or argument. Include a space before the question mark. This form of help is called command syntax help, because it reminds you which keywords or arguments are applicable based on the command, keywords, and arguments you have already entered.

Router# configure ?

	memory	Configure from NV memory

	network	Configure from a TFTP network host

	overwrite-network	Overwrite NV memory from TFTP network host

	terminal	Configure from the terminal 

To redisplay a command you previously entered, press the Up Arrow key. You can continue to press the Up Arrow key to see more of the previously issued commands.

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Tip If you are having trouble entering a command, check the system prompt, and enter the question mark (?) for a list of available commands. You might be in the wrong command mode or using incorrect syntax.

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You can press Ctrl-Z or enter end in any mode to immediately return to privileged EXEC (enable) mode, instead of entering exit, which returns you to the previous mode.

More Configuration Documentation

After you have installed the hardware, checked all external connections, turned on the system power, allowed the system to boot up, and minimally configured the system, you might need to perform more complete and complex configurations, which are beyond the scope of this document. More detailed information about Layer 3 switching software can be found in the "Related Documentation" section.

The Cisco IOS software running your switch router contains extensive features and functionality. The effective use of many of these features is easier if you have more reference information.