INTERNET ACCESS VIA CABLE TV NETWORKS

Sibananda mahanta0701222279Branch-information Technology

Contents :• Introduction

• How to Access Internet using Cable TV Network

• Cable Modem

• Changes in Cable Network

• Connection

• Work Of Cable Modem

• Isolation of TV & PC

• How Fast is Cable Modem

• Real-World Performance

• Ethernet over Coaxial Adapter

• Advantages and Disadvantages

• Applications

• Conclusion

Internet data can be transferred through Cable networks

wired to the user computer.

Accessing the Internet at 10 megabits per second.

A cable modem connects to a PC using the same coaxial

cable that brings all channels to your television.

India has a cable penetration of 80 million homes, offering

a vast network for leveraging the internet access.

INTRODUCTION

Use the dial-up telephone services

provided by your Cable Company in

conjunction with a modem or ISDN adapter.

To use a Cable modem

How to access the Internet using the Cable Network

Cable modem and ISDN Adapter

Cable modem

ISDN Adapter

A "Cable Modem" is a device that allows high-speed access

to the Internet via a cable TV (CATV) network.

The cable modem attaches to computer through an Ethernet

Network Interface Card.

It takes a signal from the computer and converts it for

transmission over the cable network

Cable Modem

Changes in the Cable Network

The cable network was designed to deliver TV signals in

one direction from the Head-End to the subscribers homes.

To provide TV services Cable Operators had to recreate a

portion of the over-the-air radio frequency (RF) spectrum

within a sealed coaxial cable line.

Operators had to upgrade the cable network so that

signals could flow in both directions. Cont..

• Cable Operators assign a spectrum of signal frequencies to the cable

network.

• One spectrum is used for the signals that move from the Head-End

towards the cable subscriber.

• Another spectrum of signal frequencies are used for the signals that

move from the cable subscriber towards the Head-End.

• By replacing existing one way amplifiers with two way amplifiers Cable

Operators are able to separate the upstream and downstream signals

and amplify each direction separately in the right frequency range

How does it connect?

A Traditional Cable network Cont..

A Modern Cable network Cont..

• Ethernet 10BaseT is emerging as the most predominant method.

How Cable Modem Work

Your Cable Company supplies you with a connection to your home

which in turn is connected to a splitter box.

One spur from the splitter box is connected to your TV through a TV

Adapter, the other being connected to your Cable Modem, which in

turn is connected to your computer through an Ethernet

connection.

Cable modems can be part modem, part tuner, part encryption /

decryption device, part bridge, part router, part NIC card and part

Ethernet hub.

Isolation of TV & PC

At the connecting point the feeding of the data into the TV cable

network.

The modem with an Ethernet interface.

They will be connected by means of a splitter at the system

outlet of the subscriber.

The system uses the frequency range from 5 MHz until 30 MHz,

which is not used from TV programs.

How fast is a Cable Modem

Cable modem speeds vary widely

• Depends on the cable modem system

• Cable network architecture

• Traffic load.

In the downstream direction (from the network to the computer), network

speeds can be up to 27 Mbps

• BUT, this is an aggregate amount of bandwidth that is shared by users.

Few computers will be capable of connecting at such high speeds or have

exclusive access to the network

• A more realistic number is 1 to 3 Mbps.

Cont..

How fast is a Cable Modem

In the upstream direction (from computer to network), speeds can

be up to 10 Mbps.

• However, most modem producers have selected a more

optimum speed between 500 Kbps and 2.5 Mbps

• AND, many cable operators limit the upstream bandwidth to

128 or 384kbs

An asymmetric cable modem scheme is most common. The

downstream channel has a much higher bandwidth allocation

(faster data rate) than the upstream,

primarily because Internet applications tend to be asymmetric in

nature. Cont..

How fast is a Cable Modem

Activities such as World Wide Web (http) navigating

and newsgroups reading (nntp) send much more data

down to the computer than to the network.

Mouse clicks (URL requests) and e-mail messages are

not bandwidth intensive in the upstream direction.

Image files and streaming media (audio and video) are

very bandwidth intensive in the downstream direction.

Real-World Performance

The theoretical performance of a Cable Modem is based upon all

other devices being able to work at the same speed and

performance as the Cable Modem.

However, in a similar way that the actual usable bandwidth on a

10Mbps Ethernet connection reduces to a 4Mbps, so too will the

performance of a Cable Modem connection be reduced.

The Cable network itself will suffer the same problems of Internet

performance as any other Internet Service Provider (ISP).

Cont..

Real-World Performance

Although performance to services on the cable network

itself can be amazingly fast, access to 'the outside world'

will be slowed down by the performance of other

connections on the way.

As usage on your segment grows (as more customers are

added) the bandwidth must be shared by more people.

Support for Multiple PCs

A cable modem can provide Internet access to multiple

PCs, if they are connected via a local area network

(LAN)

Cable modems typically have an Ethernet output, so

they can connect to the LAN with a standard Ethernet

hub or router

Each PC must have an assigned IP address

• The cable ISP usually sells at a premium of $5-$10 a

month per PC

• NAT (Network Address Translation) can allow

multiple PCs to "hide" behind a single IP Address

Ethernet over Coax Adapter

Ethernet Coaxial Adapter :-

Ethernet over Coax Adapter The Ethernet over Coax adapter provides a simple and

inexpensive way to create a reliable home network, without

running CAT5 cables through your walls.

It delivers high speed internet, voice and video over coaxial cable.

Ideal for homes, apartment buildings or hotels seeking to add

high-speed internet capabilities over existing coaxial TV cables.

Advantages

High Availability

High Bandwidth to Low Coast

High Speed Data Access

Always on Connectivity

Limitation

Cable connections are not available in every

neighbourhood, Because cable connections are

‘Always on,’ one needs a firewall and

activation of other security features so as to

protect the computer

Applications

Connect set-top boxes, personal computers, game consoles,

broadband modems etc. to your home network instantly.

Add high-speed internet, digital voice and video access to

any room with a coaxial TV cable.

Ideal for homes, apartment buildings or hotels seeking to

add high-speed.

Conclusion

Cable TV has a strong reach to the homes and therefore

offering the Internet through cable be a scope for furthering

the growth of internet usage in the homes.

The cable is an alternative medium for delivering the Internet

Services in the US, there are a million homes with cable

modems, enabling the high-speed internet access over cable

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