This document discusses DSL and ADSL internet technologies. DSL uses telephone lines to provide internet access using higher frequency bands, allowing data and voice services simultaneously. Download speeds for consumer DSL typically range from 256 kbps to 100 Mbps, while upload speeds are lower. ADSL is an asymmetric type of DSL that provides higher download than upload speeds, with typical speeds of 5 Mbps down and 1 Mbps up. Advantages include using existing phone lines, integration with other technologies, and faster speeds than dial-up. Disadvantages include limited availability, high installation costs, and security risks without firewall protection.

1. DSL and ADSL
Prepaid By: Anil Shrestha
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2. 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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3. 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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4. 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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5. 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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6. 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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7. 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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8. 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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9. 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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10. 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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