6TASYS101-1E
TOTAL ACCESS 3000/3010
SYS-101
Page 37 of 46
Total Access
®
3000/3010 System Manual
© 2003, ADTRAN, Inc.
5.2 Loop Access Solutions
See Figure 18 for some of the loop side carrier devices and arrangements that
interface to the Total Access 3000/3010.
4 T1 Circuits
HRE
HTU-R
NID
FNID
2 HDSL
4-wire
T1
circuit
HDSL
4-wire
circuit
ADTRAN
Loop
Support
System
Optical DS2
Remote
Chassis
2 Optical Fibers
FT1 2-wire circuit
(SDSL)
T1
circuit
HD-10
ISDN
Terminal
10
U-interfaces
Total Access 3000/3010
Local Loop
Figure 18. TDM Loop Devices
5.2.1 HDSL/HDSL2
The strategic importance of HDSL/HDSL2 is the speed and ease with which HDSL/
HDSL2-provisioned T1 circuits can be brought on line. HDSL is designed for a
nominal loop length of 12,000 feet over two pairs of 24 AWG cable. HDSL2 is
designed for a nominal loop length of 12,000 feet over a single pair of 24 AWG cable.
Because this falls within the majority of typical, traditional T1 local circuits, HDSL
was marketed as “repeaterless T1” technology. Within the 12 kilo-foot basic span,
HDSL requires no additional electronic components in the loop itself.
With HDSL/HDSL2 there is also less need for circuit engineering. Additionally,
HDSL is highly noise resistant. Thus, circuit pairs in a cable sheath are simply chosen
from those that are available. No special separation or assignment criteria are required.
Existing line facilities can be more easily reused, reducing new investment in outside
cable plant.
Another useful characteristic of HDSL/HDSL2 is a tolerance for bridge taps. There
may be a total of 2,500 feet of bridge taps on a circuit. Any single tap may not be
greater than 2,000 feet.
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