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Basic Cisco Router Setup and Configuration

Basic Cisco Router Setup and Configuration

November 30, 2018 in Corporate IT Training, Cisco / by Sara Lamb

Getting a Cisco router up and working is a fairly straightforward endeavor, as there are really only a few items that need to be addressed. Let’s take a look at the basic instructions that will help you configure and setup the router. Once these basic settings are established, the configuration can be made more complex given the individual needs specific to each use.

How to Setup a Cisco Router

When a Cisco router boots for the first time, it will ask if the user would like to review the set of prompts to configure. You can go through these prompts or ignore them and choose to configure the router manually, as most engineers do. Once initially booted, all that is required to configure the router is a USB cable or serial rollover cable. After a connection is made, the initial basic configuration of the device can begin.

Once connected, the user will first see a user exec mode prompt (as long as the user entered ‘no’ in the initial configuration dialog). We need to be in privileged exec mode in order to continue with the configuration. Enter the ‘enable’ command to access this prompt. Once in this mode, the user should be able to access all the commands necessary to alter the configuration of the router. Entering the ‘configuration terminal’ (or ‘conf t’) command will allow the user to do this. This initial config mode is called the Global configuration mode. Here is where domain name, passwords, and the hostname can be configured.

Enter the ‘hostname hostname’ command to configure the hostname of the router. Once entered, the hostname should be reflected in the prefix of the prompt. The domain name can now be configured by entering ‘ip domain-name domain-name’ command.

The user can now move on to setting up the password. Configure the enable password by entering the ‘enable secret password’ command. Setting up the password will prevent unwanted users from getting into privileged exec mode, though it should be known that local users will still be able to access user exec mode.

Setting up interfaces for LAN and WAN

Next, we will cover configuring the Fast Ethernet interfaces for LAN and WAN. Fast Ethernet LAN interfaces are automatically configured as part of the default VLAN, so they are not set up with individual addresses. Access is through the VLAN itself. You can find more information about creating VLANs here.

The procedure for configuring Fast Ethernet WAN interfaces will depend on what model router you are working with. The Cisco 1811 and 1812 routers have two Fast Ethernet interfaces for WAN, while the 1801, 1802, and 1803 routers have one ATM interface for WAN connection.

To configure the Fast Ethernet WAN interface, set up the interface with ‘interface fastethernet number value’. The user can then set the IP address and subnet mask for the specified Fast Ethernet interface with ‘ip address ip address – subnet mask’.

To configure the ATM WAN interface, first enter ‘interface atm0’ to go to the interface configuration mode. Then the user can set the IP address and subnet mask for the ATM interface with ‘ip address ip address – subnet mask’.

One final important step is left: enabling the interface. This can be accomplished by entering ‘no shutdown’ while still in the interface configuration mode.

Configuring command-line access to the router

Access to the router, when connected to the console port, is not password protected by default. This means that any user with physical access will be able to access user exec mode. You can alter this by configuring a password on the console line by entering ‘line console 0’ to enter line configuration mode. Then the user can issue the ‘password password’ command to set the password.

Lastly, we will look at enabling Telnet access to the router. You can configure this access through VTY terminal configuration mode. Most VTY lines used for Telnet connections are labeled 0-4. Enter ‘line vty 0 4’ to access to the mode. From here the user will enter ‘login’ to enable a login prompt that will show when other users are attempting to access the router through the terminal lines. The command ‘password’ will allow us to set the password for this access.

This review of the basic setup instructions for a Cisco router is intended to be a quick reference guide designed to get the device working in a short about of time. For a more thorough review of the setup process, it may be helpful to visit Cisco’s online configuration guide. For more in-depth training classes, see the Cisco training class schedule here.

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