Computers and other data networking devices that need to be connected to a data network will either use a copper cable, fibre optic cable or will associate with a wireless access point using radio waves as the medium. If you are connecting in to an Ethernet switch or networking port on something like a home broadband router then a copper cable will be required to provide the physical medium over which your data communications protocols will run.
TCP/IP is by far the most common data networking protocol suite in use, with Ethernet being the most common data-link protocol. Ethernet runs over 2 pairs of copper wires, with one pair being used for transmit and the other pair for receiving data signals between the two connected devices, one of which will be your computer and the other will be some form of data-link layer switch.
Cables for use with networking are known by a number terms including, Computer Cable, Ethernet Cable, Network Cable, Patch Cable or even Cat5 Cable. They are all essentially the same with 8 copper wires individually encased in some form of insulating material, with the whole bundle of insulated cables further covered by a external insulation layer. These Patch Cables are sometimes referred to as Twisted Pair, where 4 pairs of wires are twisted together using a precise number of twists per metre in an attempt to combat something known as “Crosstalk”. Which essentially means stopping signals on one pair of wires from interfering with signals on another pair.
Most copper patch cables will be found with an RJ-45 modular connector on both ends to facilitate connection to the computer and Ethernet switch. The insulation on the individual wires are colour coded so that each pair of wires can be easily identified and connected in the correct manner. These patch cables evolved from cables originally designed for connecting telephones, and the most common standard for telephone cables was know as Category 3 or Cat3 for short. Unfortunately these cables were not very good at carrying the high speed data in our modern data networks, and these days we will use a Cat5, Cat5e or Cat6 cable.
Category 5 cable is cable of giving a performance of up to 100Mhz and can be used for 10Mbps, 100Mbps or 1000Mbps Ethernet signals using the 10BaseT, 100BaseTX or 1000BaseT standards. For the 1000BaseT standard it is often recommended that Category 5e (enhanced) is used, due to its ability to better combat crosstalk. Cat5e still has the bandwidth capability as the original Cat5 standard of 100Mhz. A lot of professional organisations are now employing Category 6 cable in an attempt to future proof their data networks because it has a bandwidth capability of up to 250Mhz and even better, improved crosstalk specification. In addition, Cat6 cable can be used with the newer 10GBaseT standard for 10 Gigabit Ethernet. For most home users Cat5e will provide sufficient performance for most applications, but it you wish to pay a little extra for Cat6 cable then it is fully backward compatible.
Ethernet cables do have restrictions on the maximum length of cable that may be used and this is due to feature employed by the Ethernet standard known as collision detection. The maximum distance for any Ethernet Patch Cable whether it be Cat5, Cat5e or Cat6 is 100 metres when used in half-duplex mode. If you require a longer run of cable then a repeater or bridge would have to be used, otherwise you could experience some performance problems.
You can buy Ethernet Patch Cables in various lengths or even buy a roll of cable if you need many cables and feel confident at securing the RJ-45 connectors. For the home user, buying a patch cable in an appropriate length is easy and the cables come in a wide range of colours so that you can colour code a network.
There are occasions when you might want to connect two computers or two Ethernet switches together. If you need to do this then you will need what is known as a Crossover cable, unless your switches have the capability to detecting the type of connection. Crossover cables have pins 1 to 3 and 2 to 6 crossed over from end to end, and other instances when you might need a crossover cable are when you need to connect a Router to Router, Hub to Hub or Hub to Switch. ul3271