Ethernet Cabling

Ethernet cabling is an important discussion, especially if you are planning on taking the Cisco exams. Three types of Ethernet cables are available:

1. Straight-through cable
2.  Crossover cable
3.  Rolled cable

We will look at each in the following sections.

Straight-Through Cable
The straight-through cable is used to connect

1- Host to switch or hub

2-Router to switch or hub
Four wires are used in 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 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.

Crossover Cable
The crossover cable can be used to connect

1.  Switch to switch
2.  Hub to hub
3.  Host to host
4.  Hub to switch
5.  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 1.23 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.

Rolled Cable

Although rolled cable isn’t used to connect any Ethernet connections together, you can use a rolled Ethernet cable to connect a host to a router console serial communication (com) port. If you have a Cisco router or switch, you would use this cable to connect your PC running HyperTerminal 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.