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• Unshieldedtwisted pair (UTP)

• Shieldedtwisted 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 categoriesCategory 1 Data to < 100kbps Voice only (Telephone)

Category 2 Data to 4 Mbps (Localtalk)

Category 3 Data to 10Mbps (Ethernet)

Category 4 Data to 20Mbps (Token ring)

Category 5 Category 5e

Data to 100Mbps (Fast Ethernet) Data to 1000Mbps (Gigabit Ethernet)

Category 6Category 6a

Data to 1000Mbps (Gigabit Ethernet)Data to 10Gbps (Gigabit Ethernet)

Category 7 Category 7a

Data to 10 Gbps (Gigabit Ethernet) Data to 100 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 end2. Untwist wire

ends3. Arrange wires4. Trim wires to size5. Attach connector6. Check7. Crimp8. 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.)

Hub Switch Router Computer

Hub

Switch

Router

Crossover

Crossover

Straight

Crossover

Crossover

Straight

Straight

Straight

Crossover

Straight

Straight

Crossover

Computers Straight Straight Crossover 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• Leaǀ e about ½” of ǁ ires

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 – Jacket2 – Shield-foil3 – Drain wire4 – 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

coaxialand 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

amale 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 ofa 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.)

Coaxial Connector (cont.)

Optical Fiber

• Fibers of glass• Usually 120 micrometers in diameter• Used to carry signals in the form of light

overdistances 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 wherelight 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 to connect.

Fiber Optic Connector (cont.)

ST Connector

SC Connector