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Digital Subscriber Lines,
or
DSL,
are technologies that enable the transmission of digital data over
the wires of a local telephone network. DSL may be classified
into either asymmetric DSL (ADSL) or symmetric DSL (SDSL). In ADSL, the flow rate of
digital data in one direction is higher than the other direction,
which is why it is asymmetric. In SDSL, on the other hand, the
data flow rates in both directions are equal. Table 1 below
summarizes the characteristics of various ADSL and SDSL types.
Table 1.
Types of Digital Subscriber Lines (DSL)
|
Type |
Upstream Rate
(bps) |
Downstream Rate (bps) |
Cable
Pairs Required |
Maximum Distance (feet) |
|
Asymmetric |
|
|
|
|
|
Carrierless Amplitiude Phase
(CAPDSL) |
64K
640K |
1.544M
6.312M |
1
1 |
8,000
12,000 |
|
Discrete MultiTone
(DMTDSL) |
176K
224K-260K |
1.544M
6.312M |
1
1 |
18,000
12,000 |
|
Rate
Adaptive
(RADSL) |
128K -
1M |
600 K
- 7 M |
1 |
18,000
- 25,000 |
|
Very
High Bit Rate
(VDSL) |
1.6M -
2.3M |
12.96M
25.82M
51.84M |
1
1
1 |
4,500
3,000
1,000 |
|
Symmetric |
|
|
|
|
|
High
Bit Rate(HDSL) |
1.544M
2.048M |
1.544M
2.048M |
2
3 |
12,000
12,000 |
|
Single
Line
(SDSL) |
1.544M
- 2.048M |
1.544M
- 2.048M |
1 |
10,000 |
|
ISDN
(DSL) |
128K |
128K |
1 |
18,000 |
See Also:
More Tables; More
Articles
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