ADC H4TU-C-319 List 1 Line Unit A5LB Test Procedure, A5LB Addressable Repeater Loopback Commands

LTPH-UM-1031-03, Issue 3 Testing

A5LB Test Procedure

Using the codes listed in Table 18, a network tester can activate NLOC or NREM loopbacks (or SMJK, if enabled). A tester at the customer premises can activate CLOC or CREM loopbacks.

Table 18. A5LB Addressable Repeater Loopback Commands

Name	Binary Code (a) (Hexadecimal Equivalent)	Description
ARMING or NI LPBK (inband)	11000-11000 ...	Arming code
ARMING or NI LPBK (ESF Data Link)	1111-1111-0100-1000 (FF48)	Arming code
IR LPDN or DISARM (inband)	11100-11100 ...	Disarming code
IR LPDN or DISARM (ESF Data Link)	1111-1111-0010-0100 (FF24)	Disarming code
IOR LPBK (NLOC or CREM)	1101-0011-1101-0011 (D3D3)	H4TU-C loopup
230-232 bit errors
229-231 bit errors (b)
ILR-1 LPBK	1100-0111-0100-0001 (C741)	Doubler-1 loopup
(NDU1 and CDU1 10 bit errors)
ILR-20 LPBK	1100-0111-0101-0100 (C754)	Doubler-2 loopup
(NDU2 and CDU2 200 bit errors)
ILR-2 LPBK	1100-0111-0100-0010 (C742)	H4TU-R loopup
(NREM and CLOC 20 bit errors)

ILR-2 LPBK (NREM or CLOC) 20 bit errors (c)

NREM—DSX-1 signal is looped back to 1100-0111-0100-0010 (C742) the network at the H4TU-R.

CLOC—DS1 signal from customer is looped back to the customer at the H4TU-R.

IR LPDN	1001-0011-1001-0011 (9393)		Loopdown (H4TU-C or H4TU-R)
IR QUERY LPBK	1101-0101-1101-0101	(D5D5)	Query loopback
IR ALTERNATE QUERY LPBK	1101-0101-1110-1010	(D5EA)	Alternate query loopback
TIME-OUT OVERRIDE	1101-0101-1101-0110	(D5D6)	Loopback time-out override
IOR POWER DOWN (H4TU-C) (d)	0110-0111-0110-0111	(6767)	Removes HDSL4 line power

(a)The leftmost bit arrives first in all sequences. The detection algorithm functions reliably with a random 10-3BER on the facility. The entire arming and loopback sequence can also be initiated at the remote H4TU-R location.

(b)The H4TU-R identifies CREM (and the H4TU-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 H4TU-R and H4TU-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 H4TU-R and H4TU-C transmit for a CI and NI loopback.

(c)The H4TU-R is assigned the ILR-2 loopback code. It responds with 20 bit errors (excluding the frame bits).

(d)The IOR Power Down code must remain present for the duration of the power down mode. When this code is removed, the system returns to its normal unlooped and unarmed state.

H4TU-C-319 List 1 September 12, 2003 53