Router Configuration

Modern routers commonly have some sort of Graphical User Interface (usually web based) that allow you to access the operating system and configure the router.  However as was explained earlier, most routers rely on command line interfaces so that the routers processing power is concentrated on doing its main job which is to forward packets.  Also if you learn the command line interface, it can be quicker to troubleshoot and configure in some cases.  Also Cisco routers and switches all use a common CLI and once you have learned it, you can apply it to different types of device. It is worth the effort!

Cable Types
You should already be familiar with the different types of cable connection, however here is a short refresher prior to starting to configure the router.

An Ethernet Straight Through Cable

An Ethernet straight through cable will look similar to the one above – the cable colours will be the same on both sides.  This is a 568B-568B cable. Sometimes you will find 568A-568A cables these start with green at the far left.  As long as the cable has either 568A on both sides or 568B on both sides then it’s a straight through cable.

An Ethernet Crossover Cable

An Ethernet crossover through cable will look similar to the one above – the cable colours will be the different on both sides.  This is a 568A-568B cable.


A Rollover Cable

A Rollover cable will look similar to the one above, it usually has a DB9 connection (or adaptor) for a serial port and the other end is an RJ45 connection.  The cable is usually flat (which assists in creating the “rollover” ie pin 1 to pin 8, 2 to 7 etc

A Serial Cable
The serial cable is used to connect to a wan.  For the purposes of the labs we will simulate a wan, and we will connect these together.

The Cable shown above is the DTE end.


The cable below is the DCE end

Configuring a router via Command Line Interface (CLI)
In order to configure a router via the command line interface, you required to connect a rollover cable to the console port on the router. (Shown below)


The other end of the rollover cable should be connected to a serial port on a computer.  Often laptops do not have serial connections so a USB to Serial adaptor may have to be obtained.

Once you have connected the cable you need to run a piece of terminal emulator software such as HyperTerminal or Putty.  You can download putty from

Whether you are setting up HyperTerminal or Putty, you will require to configure some settings,

• Select COM port (this relates to the com port that you have connected to.  This is usually 1 or 2).

• Set the BAUD rate to 9600.

If your terminal emulation software asks; The parity bit should be 0 and the Data bits should be 8.

When the connection is initiated (by clicking open) you will see the following screen


Now you can start the process of configuring your router.  You must do this prior to connecting your router to the network. as all of its ports will be administratively set in an off position (called ‘down’)

Next – Router OS