Networking Cables and Connections

In order for the communication to take place, cables play important role. Cable is the medium through which information usually moves from one network device to another. There are several types of cable which are commonly used with LANs. The type of cable chosen for a network is related to the network's topology, protocol, and size.
There are various types of cables used in networks as follows.

• Unshielded Twisted Pair (UTP) Cable
• Shielded Twisted Pair (STP) Cable
• Coaxial Cable
• Fiber Optic Cable

Twisted Pair Cables:
Twisted pair cabling is a type of wiring in which two conductors of a single circuit are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources; for instance, electromagnetic radiation from unshielded twisted pair (UTP) cables, and crosstalk between neighboring pairs. In balanced pair operation, the two wires carry equal and opposite signals and the destination detects the difference between the two. This is known as differential mode transmission. Noise sources introduce signals into the wires by coupling of electric or magnetic fields and tend to couple to both wires equally. The noise thus produces a common-mode signal which is cancelled at the receiver when the difference signal is taken.

Categories Of UTP Cable:
It has been categorized into three categories based on the equipment that are being connected through these wires.
i. Straight Through Cable
ii. Cross Over Cable
iii. Roll Over Cable

Explanation:

Straight Through Cable:
Straight through cables are used to connect different devices like Switch to PC. Switch to Router. Router to Switch etc. Straight-through cables are used when each end of the communication transmits and receives on different pairs.

Cross Over Cable:
In a cross over the cable, the send and receive wires are "crossed over", meaning the wires are opposite on each end. This allows two PCs to talk to each other, has it connects the send of one computer to the receive of the other. Hence, the cross over cables are used to connect similar devices like PC to PC , Router to Router, Switch to Switch, Hub to Hub etc.

Roll Over Cable:
Roll over cables are used to connect to the console port of the device. It gets the name rollover because the pin outs on one end are reversed from the other, as if the wire had been rolled over and you were viewing it from the other side.

Transmission Pins:
Devices that transmit on 1,2 and receive on 3,6
1) PC
2)Router
3)Wireless Access Point AP
4) Networked printers
Devices that transmit on 3,6 and receive on 1,2
1)switch
2)bridge
3)hub



Required Equipment:
In order to make a network cable you need the following equipment.
i. Cat5, Cat5e cable.

CAT5 cable usually contains four pairs of copper wire, Fast Ethernet communications only utilize two pairs. A newer specification for CAT5 cable -CAT5 enhanced ("CAT5e" or "CAT 5e")- supports networking at Gigabit Ethernet[ speeds (up to 1000 Mbps) over short distances by utilizing all four wire pairs, and it is backward-compatible with ordinary CAT5.

ii. A connector named RJ-45.

RJ45 connectors feature eight pins to which the wire strands of a cable interface electrically. Standard RJ-45 pin outs define the arrangement of the individual wires needed when attaching connectors to a cable.

iii. Crimping tool:

Use to crimp the cable inside RJ 45 connector. 

iv. Wire stripper or Knife:

You can use a knife too to cut the wire open. In order to make different combinations of it. we will have to cut the upper protective coating and bring out the eight wires. 

Category	Speed	Use
1	1 Mbps	Voice Only (Telephone Wire)
2	4 Mbps	LocalTalk & Telephone (Rarely used)
3	16 Mbps	10BaseT Ethernet
4	20 Mbps	Token Ring (Rarely used)
5	100 Mbps (2 pair)	100BaseT Ethernet
5e	1,000 Mbps	Gigabit Ethernet
6	10,000 Mbps	Gigabit Ethernet

Auto-MDIX:
Auto-MDIX (automatic medium-dependent interface crossover) is a computer networking technology that automatically detects the required cable connection type (straight-through or crossover) and configures the connection appropriately, thereby removing the need for crossover cables to interconnect switches or connecting PCs peer-to-peer. When it is enabled, either type of cable can be used and the interface automatically corrects any incorrect cabling. For Auto-MDIX to operate correctly, the speed on the interface and duplex setting must be set to "auto".

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