Testing LTPH-UM-1049-02, Issue 2
64 January 9, 2002 H2TU-C-319 List 4E
A3LB and A4LB Test Procedures
The H2TU-C can be looped back by sending the Addressable Office Repeater (AOR) LPBK activation code
1111-1111-0001-1110 (FF1E) for at least 5 seconds. This causes the H2TU-C to enter the NLOC state. The
Loopback Time-out setting (see “Setting the Loopback Time-Out Option” on page 57) determines the duration of
this loopback unless it is overridden by the reception of a second identical 16-bit loopup command before the timer
expires. When this time-out override state exists, the only way to loop the H2TU-C down is to issue one of the
three loopdown commands listed in Table 25. The automatic time-out mode is restored during subsequent
loopback sessions.
Table24 summarizes the codes required to execute Addressable 3 and 4 (A3LB and A4LB) repeater loopback
commands that are identified in H2TU-C HDSL2 products. All code sequences must be present for at least 5
seconds. Information specific to HiGain HDSL2 regenerators is shown in bold.
SmartJack Test Procedure
The HiGain H2TU-R supports the standard SmartJack loopback which can emulate a Network Interface Device
(NID) for the purpose of loopback testing of the HiGain HDSL2 circuit. SMJK and NREM loopbacks perform the
same functions, but their initiation differs. SMJK indicates that the loopback was initiated by any of the three
SmartJack loopup commands listed in Table 25. NREM, on the other hand, is initiated by the 3-in-7 in-band
command or by a command issued from the maintenance terminal.
The SmartJack loopback option, LPBK, enables or disables the ability of the H2TU-R to emulate the family of
SmartJack loopback commands listed in Table25.
Table 24. Addressable Repeater Loopback Commands (A3LB and A4LB)
Name Description Binary Code (a) (Hexadecimal Equivalent)
(a) The leftmost bit arrives first in all sequences. The detection algorithm functions r eliably with a random 10-3 Bit Error Ratio (BER)
on the facility. The entire loopback sequence can also be initiated at the remote H2TU-R location.
NLOC H2TU-C loopup from NI 1111-1111-0001-1110 (FF1E)
CREM H2TU-C loopup from CI 0011-1111-0001-1110 (3F1E)
NREM H2TU-R loopup from NI 1111-1111-0000-0010 (FF02)
CLOC H2TU-R loopup from CI 0011-1111-0000-0010 (3F02)
Table 25. SmartJack Loopup and Loopdown Commands
In-Band 2-in-5
Loopup Code In-Band 3-in-5
Loopdown Code (a)
Out-of-Band
ESF-FDL Loopup
Codes
Out-of-Band
ESF-FDL Loopdown
Codes (a)
(a) These universal loopdown codes can release any and all exist ing loopup states regardless of loopback direction or method of
initiation. The codes are permanently enabled and independent of all loopback option settings, including the LPBK option.
In-Band 1-in-6
Loopup Code In-Band 1-in-3
Loopdown Code (a)
11000 111000 1111-111-0100- 1000 1111-1111-0010-0100 100000 100