Unit – III Network Media and Hardware

3.1 Transmission Media: Unguided and Guided media, Wired

and Wireless, UTP, Coaxial and Fiber optical cable

3.2 Types of Connectors: RJ-45, RJ-11, BNC, BNC –T, BNC

Terminator, Fiber optic connectors:- Subscriber Channel(SC),

Straight Tip(ST), Mechanical transfer – registered jack(MT-RJ)Straight Tip(ST), Mechanical transfer – registered jack(MT-RJ)

connectors

3.3 Network Interface Card (NIC), ARCNET, Ethernet.

3.4 Network connecting devices: Repeater, Hub, Bridge,

Switch , Router, Gateway, Access point, Wireless Access points

(i) Twisted Pair Cable –

It consists of 2 separately insulated conductor wires wound about each other. Generally,

several such pairs are bundled together in a protective sheath. They are the most widely

used Transmission Media. Twisted Pair is of two types:

Unshielded Twisted Pair (UTP):

This type of cable has the ability to block interference and does not depend on a physical

shield for this purpose. It is used for telephonic applications. Advantages:

Least expensive

Easy to install

High speed capacity

Disadvantages:

Susceptible to external interferenceSusceptible to external interference

Lower capacity and performance in comparison to STP

Short distance transmission due to attenuation

Shielded Twisted Pair (STP):

This type of cable consists of a special jacket to block external interference. It is used in fast-

data-rate Ethernet and in voice and data channels of telephone lines. Advantages:

Better performance at a higher data rate in comparison to UTP

Eliminates crosstalk

Comparatively faster

Disadvantages:

Comparatively difficult to install and manufacture

More expensive

Bulky

(ii)CoaxialCable –

It has an outer plastic covering containing 2 parallel conductors each having a separate insulated

protection cover. Coaxial cable transmits information in two modes: Baseband mode(dedicated

cable bandwidth) and Broadband mode(cable bandwidth is split into separate ranges). Cable TVs

and analog television networks widely use Coaxial cables.

Advantages:

High Bandwidth

Better noise Immunity

Easy to install and expand

Inexpensive

Disadvantages:

Single cable failure can disrupt the entire network

(iii)OpticalFibreCable –

It uses the concept of reflection of light through a core made up of glass or plastic. The core is

surrounded by a less dense glass or plastic covering called the cladding. It is used for

transmission of large volumes of data.

Advantages:

Increased capacity and bandwidth, Light weight,Less signal attenuation

Disadvantages:

Difficult to install and maintain

High cost

Fragile

2. Unguided Media:

It is also referred to as Wireless or Unbounded transmission media.No physical medium is

required for the transmission of electromagnetic signals.

Features:

Signal is broadcasted through air

Less Secure

Used for larger distances

There are 3 major types of Unguided Media:

(i) Radio waves –

These are easy to generate and can penetrate through buildings. The sending and receiving

antennas need not be aligned. Frequency Range:3KHz – 1GHz. AM and FM radios and antennas need not be aligned. Frequency Range:3KHz – 1GHz. AM and FM radios and

cordless phones use Radio waves for transmission.

Further Categorized as: (i) Terrestrial and (ii) Satellite.

(ii) Microwaves –

It is a line of sight transmission i.e. the sending and receiving antennas need to be properly

aligned with each other. The distance covered by the signal is directly proportional to the

height of the antenna. Frequency Range:1GHz – 300GHz. These are majorly used for mobile

phone communication and television distribution.

(iii) Infrared –

Infrared waves are used for very short distance communication. They cannot penetrate

through obstacles. This prevents interference between systems. Frequency Range:300GHz

– 400THz. It is used in TV remotes, wireless mouse, keyboard, printer, etc

USB (Universal Serial Bus)

Universal Serial Bus, or USB, is a computer standard designed to eliminate the guesswork in

connecting peripherals to a PC. It is expected to replace serial and parallel ports. A single USB

port can be used to connect up to 127 peripheral devices, such as mice, modems, keyboards,

digital camera's, printers, scanners, MP3 players and many more. USB also supports Plug-and-

Play installation and hot plugging.

USB 1.1 standard supports data transfer rates of 12 Mbps.

USB 2.0 (Also referred to as Hi-Speed USB) specification defines a new High-speed transfer rate

of 480 Mb/sec.

USB 2.0 is fully compatible with USB 1.1 and uses the same cables and connectors. USB has with

two connector types. The first is Type A (on the right), This connector connects to the PC's USBtwo connector types. The first is Type A (on the right), This connector connects to the PC's USB

port. The Type B (on the left) connector and is for connecting to the relevant peripheral. Where

as the type A connector is truly standard, the Type B connector could be changed in size etc.

with individual peripherals meaning they require there own unique cables.

RJ-11 (Registered Jack)

Standard telephone cable connectors, RJ-11 has 4 wires (and RJ-12 has 6 wires). RJ-11 is

the acronym for Registered Jack-11, a four- or six-wire connector primarily used to

connect telephone equipment.

RJ-11 PinSignal Name1VCC (5 volts regulated)2Power Ground3One Wire Data4One Wire

Ground

RJ-11 Pin Signal Name

1 VCC (5 volts regulated)

2 Power Ground

3 One Wire Data

4 One Wire Ground

RJ-45 (Registered Jack)

The acronym for Registered Jack-45 is RJ-45. The RJ-45 connector is an eight-wire connector

that is commonly used to connect computers to a local area network (LAN), particularly

Ethernet LANs. Although they are slightly larger than the more commonly used RJ-

11 connectors, RJ-45s can be used to connect some types of telephone equipment.

F-Type

The F connector is a type of RF connector commonly used for cable and universally for satellite

television. They are also used for the cable TV connection in DOCSIS cable modems, usually with

RG-6 tri-shield cable. The F connector is inexpensive, yet has good performance up to 1 GHz.

One reason for its low cost is that it uses the center wire of the coaxial cable as the pin of the

male connector. The male connector body is typically crimped onto the exposed outer braid.

Female connectors have a 3/8-32 thread. Most male connectors have a matching threaded

connecting ring, though push-on versions are also available.connecting ring, though push-on versions are also available.

ST (Straight Tip) and SC (Subscriber Connector or Standard Connector)

Fiber network segments always require two fiber cables: one for transmitting data, and one

for receiving. Each end of a fiber cable is fitted with a plug that can be inserted into a

network adapter, hub, or switch. In the North America, most cables use a square SC

connector (Subscriber Connector or Standard Connector) that slides and locks into place

when inserted into a node or connected to another fiber cable, Europeans use a round ST

connector (Straight Tip) instead.

SC connector

ST connector

Fiber LC (Local Connector)Fiber LC (Local Connector)

These connectors are used for single-mode and multimode fiber-optic cables. FC connectors

offer extremely precise positioning of the fiber-optic cable with respect to the transmitter's

optical source emitter and the receiver's optical detector. FC connectors feature a position

locatable notch and a threaded receptacle.

MT-RJ (Mechanical Transfer Registered Jack)

MT-RJ connectors are used with single-mode and multimode fiber-optic cables. The MT-

RJ connectors are constructed with a plastic housing and provide for accurate alignment via

their metal guide pins and plastic ferrules.

Used for Gigabit ethernet. To connect to modules with MT-RJinterfaces, use multimode

fiber-optic cables.

SC & ST connectors

•A NIC (Network Interface Card) provides the hardware interface between a computer and a

network. These days, almost all new computer motherboards have in-built NIC (Network

Interface Card).

•Some NIC (Network Interface Card) cards are meant for wired networks while others are for

wireless network. Most widely used wired LAN Technology is Ethernet. Ethernet based NIC

(Network Interface Card) cards are available in every local electronic hardware shops. Normal

speed rating of Ethernet based wired NIC (Network Interface Card) available these days are

10/100/1000 Mbps (Mega bits per second).

•Every computer participating in network must have at least one NIC. Computers can have

more than one NIC card also, if required.

•Every NIC (Network Interface Card) has a 48-bit globally unique identifier called as MAC

Address (Media Access Control Address) burned into its ROM chip. This MAC address is used

to deliver Ethernet Frames (packets) to a computer.to deliver Ethernet Frames (packets) to a computer.

•The NIC driver software passes the data between the Operating System and the NIC. Latest

Operating Systems include different NIC driver software for almost all major NIC vendors. If

your NIC card is not detected or not working, you must find a suitable NIC driver software

from the NIC vendor's website and install it on the computer.

•Attached Resource Computer Network (ARCnet) is a type of LAN protocol that provides

network services to 255 nodes at data rates of up to 2.5 Mbps. ARCnet is similar to token ring

and Ethernet network services.

ARCnet was fast, reliable and cheap, and it allowed different transmission systems to be merged

and implemented on same network. ARCnet was the first simple networking based solution that

provided for all kinds of transmission regardless of the transmission medium or the type of

computer. ARCnet was also the first widely available networking system for microcomputers.

Although a new ARCnet specification, ARCnet Plus, has been developed to deliver data transfer

rates of 20 Mbps, ARCnet is still used in the embedded systems market.

•An Ethernet card is one kind of network adapter. These adapters support the Ethernet

standard for high-speed network connections using cable connections.

•Although they used to be ubiquitous, wired Ethernet ports are gradually being

supplanted in computers by Wi-Fi networking capability, which offers adequate speed

relative to Ethernet but without the cost of a large port or the hassle of running a cable

from an Ethernet jack to a PC.

•Ethernet cards are part of a category of computing hardware called network interface

cards

Repeaters • The number of nodes on a network and the length of cable used – Influence the

quality of communication on the network • Attenuation – The degradation of signal clarity •

Repeaters – Work against attenuation by repeating signals that they receive on a network •

Typically cleaning and regenerating the digital transmission in the process