Copper Media
The most common media for data transfer in local networks is copper. It remains the most common medium for connecting networking devices. Copper connect Host to devices such as router switches and hub with in a LAN. Its standard define the types of cabling, bandwidth of the communication, connectors used in the cable, maximum distance of the media etc.There are different types of the copper cable used in networking-
Unshielded Twisted Pair (UTP)-
UTP in ethernet is consisting of eight wires twisted into four colour-coded pairs and then wound inside a cable jacket. The colour pairs identify the wires for proper connection at the terminals. The EIA/TIA define the some standard for the UTP cable like cable types, cable length, connectors used in the cable, ethos of testing the cable etc.
There are several category of the UTP cable and each of them indicate the level of bandwidth performance as defined by IEEE.The category Cat 3 change to Cat 5 allowed to 100megabit transmission. In 1999 the Cat 5 standard improved to Cat5e which provide fast Ethernet gigabit transmission over UTP cable. In 2002 Cat 6 was defined that allow higher performance and less crosstalk.Cat5e is still acceptable for most LANs but Cat 6 is the current recommended standard for the gigabit connection.
The most common UTP cable connector in LAN devices is an RJ-45 connector. Most computers accessing the network through RJ-45 connector plugged into the computer network interface card at the one end and a hub or switch device at the other. The cable wires inserted into RJ-45 are not always ordered in the same way. The require order of the wires in the connector, called the pinout, varies according to where the cable fit in the network. The order of the wires in the pinout is defined by EIA/TIA 568A and 568B.The advantages of the UTP cable are its flexibility, low cost media, and that they can used for either voice or data communication. Its great disadvantage is the limited bandwidth, which restrict long distance transmission with low error rates.
UTP cable types are-
1. Straight through cable-connect a network host to hub or switches
2. Crossover cable-connect two host, two switches, two router, directly connected host to router
3. Rollover cable (Cisco cable) –connects a host serial port to a Cisco device console port.