internet access via cable tv networks
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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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