Network Cabling

Introduction 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. In some cases, a network will use only one type of cable, other networks will use a variety of cable types.

Introduction (cont.) The type of cable chosen for a network is related to the network's topology, protocol, and size. Understanding the characteristics of different types of cable and how they relate to other aspects of a network is necessary for the development of a successful network.

Common network cable types Unshielded twisted pair (UTP) Shielded twisted pair (STP) Coaxial cable Fiber optic

Twisted Pair Cabling Twisted pair cabling is often used in data networks for short and medium length connections because of its relatively lower costs compared to optical fiber and coaxial cable. To reduce crosstalk or electromagnetic induction between pairs of wires, two insulated copper wires are twisted around each other. Twisted pair cabling comes in two varieties: shielded and unshielded. Unshielded twisted pair (UTP) is the most popular and is generally the best option for school networks

Unshielded Twisted Paired (UTP) Cable The characteristics of UTP are very good and make it easy to work with, install, expand and troubleshoot. Moreover, it is cheap. UTP can be affected by radio and electrical frequency interference, there is not protective metal shield (it should not be too close to electric motors, fluorescent lights, etc.).

UTP categories Category 1Data to < 100kbps Voice only (Telephone) Category 2Data to 4 Mbps (Localtalk) Category 3Data to 10Mbps (Ethernet) Category 4Data to 20Mbps (Token ring) Category 5 Category 5e Data to 100Mbps (Fast Ethernet) Data to 1000Mbps (Gigabit Ethernet) Category 6 Category 6a Data to 1000Mbps (Gigabit Ethernet) Data to10Gbps (Gigabit Ethernet) Category 7 Category 7a Data to10 Gbps (Gigabit Ethernet) Data to100 Gbps (Gigabit Ethernet)

UTP categories (cont.) CAT1 is typically telephone wire. This type of wire is not capable of supporting computer network traffic and is not twisted. CAT2, CAT3, CAT4, CAT5 and CAT6 are network wire specifications. This type of wire can support computer network and telephone traffic. CAT2 is used mostly for token ring networks, supporting speeds up to 4 Mbps.

UTP categories (cont.) For higher network speeds (100Mbps plus) you must use CAT5, CAT6, CAT7 wire, but for 10Mbps CAT3 will suffice. CAT3, CAT4, CAT5 and CAT6, CAT7 cable are actually 4 pairs of twisted copper wires and CAT5, CAT6, CAT7 has more twists per inch than CAT3 therefore can run at higher speeds and greater lengths. UTP have a maximum length of 100 meters.

RJ45 connector

Making connections - Tools CAT5e cable RJ45 connectors Cable stripper Scissors Crimping tool

Making connections - Steps 1.Strip cable end 2.Untwist wire ends 3.Arrange wires 4.Trim wires to size 5.Attach connector 6.Check 7.Crimp 8.Test

Step 1 – Strip cable end Strip 1 – 1½” of insulating sheath Avoid cutting into conductor insulation

Step 2 – Untwist wire ends Sort wires by insulation colors

Step 3 – Arrange wires (cont.) Two type of cable arrangement: Straight- Through and Crossover Straight-Through: Computer – Hub/Switch/Router Crossover: + Computer – another Computer or + a Router - another Router, or + a Switch - another Switch

Step 3 – Arrange wires (cont.) HubHubSwitchRouterComputer Hub Switch Router Crossover Crossover Straight Straight Straight Crossover ComputersStraight Crossover

Step 3 – Arrange wires TIA/EIA-568 is a set of three telecommunications standards from the Telecommunications Industry Association. – TIA/EIA 568A: GW-G OW-Bl BlW-O BrW-Br – TIA/EIA 568B: OW-O GW-Bl BlW-G BrW-Br

Step 3 – Arrange wires Straight-through cable is a Cat 5 cable that has similar wiring in both ends. Both cable ends follow either 568A or 568B. Crossover cable is a UTP cable that has one end following 568A and the other 568B

Step 3 – Arrange wires (cont.)

Step 4 – Trim wires to size Trim all wires evenly Leaǀe about ½” of ǁires exposed

Step 5 – Attach connector Maintain wire order, left- to-right, with RJ45 tab facing downward

Step 6 - Check Do all wires extend to end? Is sheath well inside connector?

Step 7 - Crimp Squeeze firmly to crimp connecter onto cable end (8P)

Step 8 – Test Does the cable work?

Shield Twisted Pair Cabling (STP) Although UTP cable is the least expensive cable, it may be easily influenced or affected by radio and electrical frequency interference (it should not be too close to electric motors, fluorescent lights, etc.). 1– Jacket 2– Shield-foil 3– Drain wire 4– Solid twisted pair

Shield Twisted Pair Cabling (STP) (cont.) The only difference between the STP and UTP cable is the additional shielding material used in STP cables. The shielding covers the full length of the cable and protects it from any external interference. STP is more expensive than UTP

Coaxial Cable (cont.) Coaxial is a type of wire that consists of a center wire surrounded by insulation and then a grounded shield of braided wire. The shield minimizes electrical and radio frequency interference. It is the primary type of cabling used by the cable television industry and is also widely used for computer networks. Although more expensive than UTP, it is much less effected by interference.

Coaxial Cable Coaxial Cable has a copper conductor lies in the center of the cable, which is surrounded by insulation. A braided or mesh outer covering surrounds the insulation.

Coaxial Cable (cont.) The two types of coaxial cabling are thick coaxial and thin coaxial. Thin coaxial – Thin coaxial cable is also referred to as thinnet. – It is a 0.2 inch diameter cable – 10Base2 refers to the specifications for thin coaxial cable carrying Ethernet signals. – The approximate maximum segment length of thin coaxial cable is 200 meters. In actual fact the maximum segment length is 185 meters.

Coaxial Cable (cont.) Thick Coaxial – Thick coaxial cable is also referred to as thicknet. – It is a 0.4 inch diameter cable – 10Base5 refers to the specifications for thick coaxial cable carrying Ethernet signals. – The maximum segment length of Thick Coaxial cable being 500 meters.

Categories of Coaxial Cables

Coaxial Connector BNC (bayonet Neill-Concelman) Connector is a male type mounted at each end of a cable. BNC T-connectors (used with the 10Base-2 system) are female devices for connecting two cables to a network interface card (NIC). BNC Terminator is placed at the end of a transmission line to prevent an signal from being reflected back from the end, causing interference. BNC Barrel Connector is used to connect two Coaxial cables together.

Coaxial Connector (cont.)

Optical Fiber Fibers of glass Usually 120 micrometers in diameter Used to carry signals in the form of light over distances more than 1 km. No repeaters needed?

Optical Fiber (cont.) SPEED: Fiber optic networks operate at high speeds - up into the gigabits BANDWIDTH: large carrying capacity DISTANCE: Signals can be transmitted further without needing to be "refreshed" or strengthened. RESISTANCE: Greater resistance to electromagnetic noise such as radios, motors or other nearby cables. MAINTENANCE: Fiber optic cables costs much less to maintain.

Fiber Optic Core – thin glass center of the fiber where light travels. Cladding – outer optical material surrounding the core Buffer Coating – plastic coating that protects the fiber.

Advantages of Optical Fibre Thinner Less Expensive Higher Carrying Capacity Less Signal Degradation Light Signals Non-Flammable Light Weight

Areas of Application Telecommunications Local Area Networks Cable TV CCTV

Type of Fibers Optical fibers come in two types: Single-mode fibers – used to transmit one signal per fiber (used in telephone and cable TV). They have small cores(9 microns in diameter) and transmit infra-red light from laser. Multi-mode fibers – used to transmit many signals per fiber (used in computer networks). They have larger cores(62.5 microns in diameter) and transmit infra-red light from LED. – Step-Index mode and Graded-Index Mode

Total Internal Reflection in Fiber

Fiber Optic Connector More than a dozen types of fiber optic connectors have been developed by various manufacturers since 1980s. The most common connector used with fiber optic cable is an ST (Straight-tip) connector. It is barrel shaped, similar to a BNC connector. A newer connector, the SC (Subscriber Connector), is becoming more popular. It has a squared face and is easier toconnect.

Fiber Optic Connector (cont.) ST ConnectorSC Connector