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Loopback Operation
A2LB Test Procedures
Using the codes listed in
enabled). A tester at the customer premises can activate CLOC, CRG, or CREM loopbacks.
Name
ARMING or NI LPBK (inband)
ARMING or NI LPBK (ESF Datalink)
IR LPDN or DISARM (inband)
IR LPDN or DISARM (ESF Datalink)
IOR LPBK (NLOC and CREM)
230-232 bit errors
(b)
229-231 bit errors
IR LPDN
IR QUERY LPBK
IR ALTERNATE QUERY LPBK
TIME-OUT OVERRIDE
FAR END NI ACTIVATE
IOR POWER DOWN (H2TU-C)
(a) The leftmost bit arrives first in all sequences. The detection algorithm functions reliably with a random 10
The entire arming and loopback sequence can also be initiated at the remote H2TU-R location.
(b) The H2TU-R identifies CREM (and the H2TU-C identifies NLOC) with 231 bit errors, including the frame bits. When framed
data is being sent in the Auto framing mode, the number of the 231 bit errors detected by the test set varies from 229 to 231,
depending on whether or not the test set counts frame errors as bit errors and on the number of frame bits contained in the
block of 231 error bits. The H2TU-R and H2TU-C generate this bit pattern in a series of discontinuous bursts containing 20-bit
errors each, including frame bits. Those test sets that do not count frame error bits as data bit errors will indicate fewer bits
than the H2TU-R and H2TU-C transmit for a CI and NI loopback.
(c) The IOR Power Down code must remain present for the duration of the powerdown mode. When this code is removed, the
HiGain HDSL2 system returns to its normal unlooped and unarmed state.
To perform the A2LB test procedures:
1
Send the inband Arming and NI LPBK code 11000 to the H2TU-R-402 for at least 5 seconds.
2
Monitor the output of the H2TU-R-402 for the return of the pattern. Return of the pattern indicates one of the
following:
•
The H2TU-R has looped up (if the SMJK Loopback option is enabled)
•
An external NID has looped up (if the SMJK Loopback option is disabled), and the H2TU-C and
H2TU-R have been armed.
3
Verify, if possible, that the H2TU-R LBK LED is either flashing yellow at 4-second intervals (indicating that
the system is armed), or is a steady yellow (indicating that it is both armed and in SMJK loopback). The
H2TU-C Status LED also flashes yellow when the system is armed.
If the Arming code is not returned after 5 seconds, the system may be armed but there is no
active loopback.
28
Table
11, a network tester can activate NLOC, NRG or NREM loopbacks (or SMJK, if
Table 11. Addressable Repeater Loopback Commands (A2LB)
Description
Arming code
Arming code
Disarming code
Disarming code
H2TU-C loopup
Loopdown (H2TU-C, H2RU, or
H2TU-R)
Query loopback
Alternate query loopback
Loopback time-out override
Unblock AIS
(c)
Removes HDSL2 line power
Binary Code
11000-11000 ...
1111-1111-0100-1000 (FF48)
11100-11100 ...
1111-1111-0010-0100 (FF24)
1101-0011-1101-0011 (D3D3)
1001-0011-1001-0011 (9393)
1101-0101-1101-0101 (D5D5)
1101-0101-1110-1010 (D5EA)
1101-0101-1101-0110 (D5D6)
1100-0101-0101-0100 (C554)
0110-0111-0110-0111 (6767)
June 16, 2000
152-402-145-02, Issue 2
(a)
(Hexadecimal Equivalent)
-3
BER on the facility.
H2TU-R-402
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