8/9/2019 Network II

1/21

Twisted-Pair Cables (contd.)

Category 3 Has four twisted pairs Can transmit data up to the rate of 10 Mbps

Category 4 Has four twisted pairs Is certified for data transmission upto 16 Mbps

Category 5 Has four twisted pairs Is certified for data transmission upto 100Mbps

8/9/2019 Network II

2/21

Twisted-Pair Cables (contd.)

Are of two kinds Unshielded twisted-pair (UTP) Shielded twisted-pair (STP)

8/9/2019 Network II

3/21

Unshielded twisted-pair and

shieldedtwisted-pair cables

Shielding

UTP

STP

8/9/2019 Network II

4/21

Unshielded Twisted-Pair(UTP)

Is commonly used in LAN cabling Is also used in telephone lines Has a maximum cable length segment of 100 m

Is susceptible to cross talk

8/9/2019 Network II

5/21

UTP cable

8/9/2019 Network II

6/21

Shielded Twisted-Pair

Uses a copper braid Has a foil wrap between and around the wire

pairs for insulation Is less susceptible to crosstalk Supports higher transmission rate

8/9/2019 Network II

7/21

STP cable

Shielding

8/9/2019 Network II

8/21

Crosstalk occurs when

signals from one line mix intoanother line

8/9/2019 Network II

9/21

Connectors Are used to connect computers Are also called RJ connectors Are of different types RJ-11 houses four cable connections

RJ 45 houses eight cable connections

8/9/2019 Network II

10/21

RJ-45 connector and jack

8/9/2019 Network II

11/21

Fiber-Optic Cable Transmits light signals instead of electrical signals Has an inner core of glass or plastic that:

Conducts lights Is surrounded by cladding which reflects light back

into the core Is a more efficient medium than others because of

its Bandwidth capacity that: is very high Can allow data rates from 100Mbps to 2 Gbps can carry the signal over large distances

does not allow cross talk

8/9/2019 Network II

12/21

Fiber-optic cable

Fiber-optic connector

Optical fiber (core) Glass cladding

Protective outer sheath(jacket)

8/9/2019 Network II

13/21

Signal Transmission

Is the way data is transmitted across a media Is classified into:

Analog signals Change continuously with time Are represented as a wave cycle

Information represents all the values in a range Digital signals Information exists in discrete states: ON or OFF, 1 or 0 Change instantaneously

8/9/2019 Network II

14/21

Signal Transmission

(contd.)Two transmission techniques are used for thetransmission of analog and digital signals

Base band transmission Uses digital signaling over a single frequency

Has devices that transmits bi-directional

8/9/2019 Network II

15/21

Base band transmission showingbi-directional digital wave

8/9/2019 Network II

16/21

Uses analog signals Divides the entire broadband into multiple channels each channel can carry a different analog system

Supports multiple simultaneous transmissions over asingle transmission media

Base band transmission showing bi-directional

digital wave Broadband transmission showing unidirectional

analog wave

Broadband transmission

8/9/2019 Network II

17/21

Broadband transmission showing

unidirectional analog wave

8/9/2019 Network II

18/21

Wireless Network

Has no cables Relies on earths atmosphere to act as the

transmission medium Is classified into:

Local area networksExtended local area networksMobile computing

8/9/2019 Network II

19/21

Wireless Local Area

Network Has the same topology as a cabled LAN Has wireless components which connect thedifferent parts of the network

Wireless computers communicate with the cablednetwork with the use of transceivers Transmission techniques include:

Infraredlaser Narrow-band(single frequency) radioSpread spectrum radio

8/9/2019 Network II

20/21

Is an inter-LAN digital connectivity specification Transmits: Voice Data Imaging Divides the available band width into 3 channels:

Two are called B channels which transmit at 64 Kbps Third is called D channel which transmits at 16 Kbps

ISDN

8/9/2019 Network II

21/21

ISDN (Contd.)

Advantages of ISDN: inexpensive dialled service

high-speed data transmission ability to send and receive voice, data, still and

moving images through the same fully digitalconnections.

Disadvantages: Costly Need special devices