6. Ethernet Cabling

Ethernet has become the de facto standard for LAN implementations. At one time, there were three competing technologies: Ethernet, Token Ring, and FDDI. Because of the cost of FDDI, it was never really implemented on a wide scale but used only for

backbone connections. Token Ring, however, was designed and heavily promoted by IBM. When Cisco purchased IBM’s networking division, this stopped any further development on Token Ring technology. Therefore, most companies that used other LAN media types have converted to Ethernet. This section will provide a review from Chapter 2 on Ethernet, as well as the types of connections and cables you’ll use to attach Ethernet devices together. 

Ethernet cables are available in different types. These are:

• Straight-through cable
• Crossover cable
• Rolled cable

(i) Straight-Through Cable

The straight-through cable is used to connect

• Host to switch or hub
• Router to switch or hub

 Four wires are used in the straight-through cable to connect Ethernet devices. It is relatively simple to create this type; Figure shows the four wires used in a straight-through Ethernet cable.

Notice that only pins 1,2,3, and 6 are used. Just connect to 1 to 1, 2 to 2, 3 to 3 , and 6 to 6 and you’ll be up and networking in no time. However, remember that this would be an Ethernet-only cable and wouldn’t work with voice, Token Ring, ISDN, and so on.

(ii) Crossover Cable

The crossover cable can be used to connect

• Switch to switch
• Hub to hub
• Host to host
• Hub to switch
• Router direct to host

 The same four wires are used in this cable as in the straight-through cable; we just connect different pins together. Figure shows how the four wires are used in a crossover Ethernet cable. 

 Notice that instead of connecting 1 to 1, 2 to 2, and so on. Here we connect pins 1 to 3 and 2 to 6 on each side of the cable.

(iii) Rolled Cable

Although rolled cable isn’t used to connect any Ethernet connections together, you can use a rolled cable to connect a host to a router console and communication (com) port.

If you have a Cisco router or switch, you would use this cable to connect your PC running Hyper Terminal to the Cisco hardware. Eight wires are used in this cable to connect serial devices, although not all eight are used to send information, just as in Ethernet networking. Figure shows the eight wires used in a rolled cable. 

These are probably the easiest cable to make because you just cut the end off on one side of a straight-through cable, turn it over, and put it back on( with a new connector). 

Once you have the correct cable connected from your PC to Cisco router or switch, you can start HyperTerminal to create a console connection and configure the device.