7.1

Chapter 7

Transmission Media

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7.2

Figure 7.1 Transmission medium and physical layer

The physical layer is responsible for movements of

individual bits from one hop (node) to the next (see bot_L2.ppt).

Note

7.3

Figure 7.2 Classes of transmission media

7.4

7-1 GUIDED MEDIA

Guided media, which are those that provide a conduit

from one device to another, include twisted-pair cable,

coaxial cable, and fiber-optic cable.

Twisted-Pair Cable

Coaxial Cable

Fiber-Optic Cable

Topics discussed in this section:

7.5

Figure 7.3 Twisted-pair cable

7.6

Figure 7.4 UTP and STP cables

7.7

Table 7.1 Categories of unshielded twisted-pair cables

7.8

Figure 7.5 UTP connector

RJ-45 (Registered Jack)

7.9

RJ-45 types

Straight-through: PC HUB/Switch or Switch Router

Crossover: PC PC, Switch Switch or Router Router

7.10

Rollover cable or also Console cable: Use this cable to

configure a Switch or Router using the Console port.

Connect the other end of the cable to PC’s COM port

and open the terminal.

RJ-45 types

7.11

Figure 7.6 UTP performance

7.12

Figure 7.7 Coaxial cable

7.13

Table 7.2 Categories of coaxial cables

7.14

Figure 7.8 BNC connectors

BNC = Bayonet Neill Concelman

7.15

Figure 7.9 Coaxial cable performance

7.16

Ethernet cables

Type Cable

Length of the

segment Topology Connector

10Base2 Thin coaxial 185 m Bus BNC

10Base5 Thick coaxial 500 m Bus AUI

10Base-T UTP, CAT3,4,5, 2-pairs 100 m Star RJ-45

100Base-TX UTP, CAT5, 2-pairs 100 m Star RJ-45

100Base-FX 62.5/125 µm, multimode 400 m Star

Fiber

conncetor

1000Base-CX STP 25 m Star RJ-45

1000Base-T UTP, CAT5, 4-pairs 100 m Star RJ-45

1000Base-SX 62.5/50 µm, multimode 275 / 550 m Star

Fiber

conncetor

1000Base-LX 9 µm, singlemode 3 - 10 km Star

Fiber

conncetor

7.17

Figure 7.10 Bending of light ray

7.18

Figure 7.11 Optical fiber

7.19

Figure 7.12 Propagation modes

7.20

Figure 7.13 Modes

7.21

Table 7.3 Fiber types

7.22

Figure 7.14 Fiber construction

7.23

Figure 7.15 Fiber-optic cable connectors

SC (Straight Contact), ST (Straight Tip), MT-RJ (Mechanical Transfer -

Registered Jack)

7.24

Figure 7.16 Optical fiber performance

850nm, 1300nm and 1550nm

7.25

7-2 UNGUIDED MEDIA: WIRELESS

Unguided media transport electromagnetic waves

without using a physical conductor. This type of

communication is often referred to as wireless

communication.

Radio Waves

Microwaves

Infrared

Topics discussed in this section:

7.26

Figure 7.17 Electromagnetic spectrum for wireless communication

7.27

Figure 7.18 Propagation methods

7.28

Table 7.4 Bands

7.29

Figure 7.19 Wireless transmission waves

7.30

Figure 7.20 Omnidirectional antenna

7.31

Radio waves are used for multicast communications, such as

radio and television, and paging systems.

Note

Microwaves are used for unicast communication such as cellular

telephones, satellite networks,

and wireless LANs.

Infrared signals can be used for short-range communication in a

closed area using line-of-sight propagation.

7.32

Figure 7.21 Unidirectional antennas