DSL and ADSL

Prepaid By: Anil Shrestha

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DSL

Digital subscriber line is a family of technologies that

provide internet access by transmitting digital data using a

local telephone network which uses the Public switched telephone

network.

DSL service is delivered simultaneously with wired telephone

service on the same telephone line.

This is possible because DSL uses higher frequency bands for data.

The bit rate of consumer DSL services typically ranges from

256 kbit/s to over 100 Mbit/s in the direction to the customer

(downstream), depending on DSL technology, line conditions, and

service-level implementation.

The ability to use the phone to make or receive calls while

connected to the Internet.

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DSL Speed of Downloading and

Uploading

Your DSL speed can change depending on how you use the network.DSL providers often advertise speed of their service using a combination of two bandwidth numbers; for example, "1.5 Mbps / 128 Kbps:“

The first number, 1.5 Mbps in this case, refers to the maximum bandwidth available for downloads. Examples of network download activities include browsing Web sites, receiving files fromP2P networks, and receiving emails.

The second number, 128 Kbps in this case, corresponds to the bandwidth available for uploads. Example of network upload activities include publishing to Web sites, sending files over a P2P network, and sending emails.

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Types of DSL

Asymmetric DSL: Asymmetric types of DSL connections provide more network bandwidth for downloading than for uploading. Typical asymmetric DSL services support 5 Mbps for downloads and 1 Mbps for uploads.

Symmetric DSL: Symmetric types of DSL connections provide equal bandwidth for both uploads and downloads. Symmetric DSL technology is popular for business-class DSL services as companies often have greater needs for transferring data. Typical symmetric DSL connections support 1.5 Mbps for downloads and uploads.

Other Types of DSL: IDSL is a hybrid DSL / ISDN technology developed along with other types of DSL but rarely used nowadays due to the relatively low speeds (128 Kbps maximum data rate) it supports.

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Advantage

Integration: DSL will easily interface with

ATM, Nx64, and WAN technology.

Telecommuting may get even easier.

Cheap line charges from the phone company.

High bandwidth

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Disadvantage

Very new technology

Limited availability

Expensive: Most customers are not willing to spend more

than $20 to $25 per month for Internet access. Current

installation costs, including the modem, can be as high as

$750.

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ADSL

Asymmetric digital subscriber line (ADSL) is a type of digital

subscriber line (DSL) technology, a data communications

technology that enables faster data transmission

over copper telephone lines.

A splitter, or DSL filter, allows a single telephone connection to

be used for both ADSL service and voice calls at the same time.

At the telephone exchange the line generally terminates at

a digital subscriber line access multiplexer (DSLAM) where

another frequency splitter separates the voice band signal for the

conventional phone network.

ADSL communication is full-duplex.

.

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ADSL Speed of Downloading and

Uploading

The top speed for ADSL lines is around 5

mbit/sec for the download, and 1 mbit/sec

for the upload.

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Advantage

Cable is a better connection overall. It is faster and more reliable.

ADSL is more secure, Cable is faster, and usually has better package deals.

Faster downloads compared to dial-up or ISDN.

No need for a second phone line - by allowing voice and data transfer at the same time (you can use the phone as normal while connected to the internet).

ADSL doesn't need to convert the data from digital to analogue and back again.

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Disadvantage

This service is not available in all locations.

ADSL connections are not available to everyone.

ADSL connections are Always on you will need a firewall

to protect your PC.

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