When and where do we need which cable?
- Hubs and switches are seen as “network devices”.
- Computers, servers and routers are seen as “host devices”.

Why do we call a router a host device and not a network device? Well try to think of it this way…if you don't configure a Cisco router it's not going to route anything for you and it's nothing more but a “computer”.
We need to enable a routing protocol ourselves…besides it will help you remember which cable you need to use.

More about routing later!

- Network device <-> Host device: straight-through cable.
- Host device <-> Host device: crossover cable.
- Network device <- -> Network device: crossover cable.

So between a computer and a switch you will use a straight-through cable.
Connect 2 switches to each other and you'll need a crossover cable, the same applies if you connect to
routers to each other. Router to computer (both host devices) you need a crossover cable
as well.

Do you know what the official name is for the blue Cisco console cable? You need this cable to configure your switch or router from your computer.
It‟s called a rollover cable.

Cisco IOS:
Just like a computer a switch or router requires an operating system to support the hardware.
Cisco IOS is the operating system that you will find on the switches and routers and some other devices like wireless access points.

When you work with Cisco routers and switches you will do most of the configuration using the CLI (Command Line Interface).

For some of you this might prove challenging in the beginning and it will take some time to become familiar with the CLI, however once you get used to it I promise that it‟s the fastest and most convenient method to configure routers or switches.

The CLI can be accesses by using the blue Cisco console cable (it‟s called a rollover cable) or remotely using telnet or SSH.

Cisco also offers a GUI (Graphical User Interface):
- CNA (Cisco Network Assistant) for switches.
- SDM (Security and Device Manager) or CCP (Cisco Configuration Professional) for routers.

SDM was the first version of the GUI but now it has been replaced by CCP.

The advantage of a GUI is that it has wizards that let you configure complex things with a few clicks.

The downside however is that:
A) you might have no idea what you are doing.
B) when you need to troubleshoot you'll need the CLI 9 out of 10 times. I'm not a big fan of the GUI but it's best to see for yourself.

We will start with the basic configuration of a cisco device.

First I will use a switch to demonstrate the CLI but the same commands work on a router.

Secondly I will demonstrate CCP on a router.

This is the topology that I am using.

First of all we need to have a switch. I have a Cisco Catalyst 3560 that I'll use for my
demonstration.

Secondly we'll need one of those Cisco console cables or we can't connect our computer to the switch.

If you don't have a COM / serial port on your computer or laptop, use your USB to serial cable.

The last thing you require is an application to connect to your serial port.

Putty is a good free application to start with, you can download it here:

http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html

When you start putty it looks like this.

Make sure you select serial and type in the correct COM port number.

If you don't know the COM port number you can look it up in the windows device manager.

You need to leave speed at 9600. Click on open and you will have access to your switch.

As soon as you power on the switch this is what it will do:
1. Check the hardware.
2. Locate the Cisco IOS image.
3. Locate and apply configuration (if available).

This is what it looks like on a real switch: Above you see that it‟s checking the flash drive of the switch. Next step is to load the IOS image that it found on the flash drive.

IOS images are stored on the flash drive in a compress format, it will be uncompressed and copied to the RAM of the switch.

Now IOS is loaded you will see something like this, you see this banner and the IOS version that I‟m running. This is a Cisco 3560 switch.

IOS will check the flash drive.

And once it's done it will do a POST (Power On Self-Test):