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64179008APL1-5A 23
4. TESTING
H2LIU
The Total Access 1000 DAT H2LIU provides
diagnostic, loopback, and signal monitoring
capabilities.
H2LIU Network Loopback
A Network Loopback can be initiated by a command
from the Test Menu, or sending loopback codes to the
H2LIU. The loopback position is a logic loopback
located within the H2LIU internal HDSL2 transceiver.
See Figure 22.
5. HDSL2 DEPLOYMENT GUIDELINES
The ADTRAN HDSL2 system is designed to provide
DS1 based services over loops designed to comply
with carrier service area (CSA) guidelines. CSA
deployment guidelines are given below:
1. All loops are nonloaded only.
2. For loops with 26-AWG cable, the maximum loop
length including bridged tap lengths is 9 kft.
3. For loops with 24-AWG cable, the maximum loop
length including bridged tap lengths is 12 kft.
4. Any single bridged tap is limited to 2 kft.
5. Total bridged tap length is limited to 2.5 kft.
6. The total length of multigauge cable containing
26-AWG cable must not exceed the following:
12 - {(3*L
26
) / (9- L
BTAP
)} (in kft)
L
26
= Total length of 26-AWG cable excluding
bridged taps (in kft)
L
BTAP
= Total length of all bridged taps (in kft)
This deployment criteria is summarized in the chart
shown in Figure 23.
DSX-1
H2TU-C
Local
Loop
HLIU Network-Side Loopback and/or
HLIU NIU Loopback
H2LIU
X
DS1
AIS
X = Signal Inactive
Figure 22. H2LIU Network Loopback
The Total Access 1000 DAT H2LIU will respond to
the industry defacto HDSL2 loopback codes as
designated in the ANSI document T1E1.4/92. A
synopsis of the method described by ANSI is
presented in Appendix A.
H2LIU Backplane Loopback
The H2LIU Backplane Loopback is a multi-port
loopback for the H2LIU circuits. When requested
from the H2LIU menus, the module places all four
H2LIU ports in a loopback state.
BCU
The Total Access 1000 DAT ATM BCU provides
IMA Diagnostic Testing consisting of Receive DRAM
Testing and Transmit DRAM Testing.
Self-Test
All modules perform a self-test when inserted into an
active Total Access 1000 DAT. The self-test checks
internal circuitry. If a module fails the self-test, that
module’s LEDs will indicate the condition. See Table
3 through Table 5 for details on LED indications.
Figure 23. HDSL2 Deployment Guidelines
0
12
11
10
9
8
7
6
5
4
3
2
1
0
1234
WORKING LENGTH OF 26 GAUGE CABLE (KFT)
WORKING LENGTH OF 24 GAUGE (OR COARSER) CABLE (KFT)
56789
2.5
2.0
1.5
1.0
0.5
0.0
TOTAL
BRIDGED
TAP
LENGTH
(KFT)
VALID CABLE LENGTHS
INVALID CABLE LENGTHS