ADTRAN AHDSL2 specifications Dbdb

Table A-1. In-Band Addressable Loopback Codes (Continued)

Function	Code	Response
Loop down1, 3	9393	When sent from the network or customer, all units currently in loopback
	1001 0011 1001	will loop down. Armed units will not disarm. In order to behave like a
	0011	smartjack, the H2TU-R will not loop down from a network loopback in
		response to the 9393 pattern if NIU Loopback is enabled.
Query Loopback1, 2	D5D5	When the pattern is sent from the network, logic errors will be injected
	1101 0101 1101	towards the network to indicate a loopback is present toward the network.
	0101	When the pattern is sent from the customer, logic errors will be injected
		towards the customer to indicate a loopback is present toward the
		customer. The number of errors injected is determined by the nearest unit
		that is in loopback. As long as the pattern continues to be sent, errors are
		injected again every 20 seconds (H2TU-C = 231 errors), (H2TU-R = 20
		errors).
Query Loop	DBDB	If the H2TU-C is in network loopback and armed, logic errors are injected
Parameters2	1101 1011 1101	towards the network upon detection of the DBDB pattern from the
	1011	network. As long as the pattern continues to be sent, errors are injected
		again every 20 seconds. The number of errors injected each time depends
		on the current status of signal margin and pulse attenuation parameters on
		each loop.
		If all HDSL2 receiver points (H2TU-C and H2TU-R) indicate pulse
		attenuation ≤ 30 dB and signal quality (margin) ≥ 6 dB, 111 errors are
		injected every 20 seconds; otherwise, 11 errors are injected every 20
		seconds. This pattern has no functionality when sent from the customer.
Loopback Time	D5D6	If the units are armed or a unit is currently in loopback when this pattern is
Out Override1, 2, 4	1101 0101 1101	sent from the network or customer, the loopback time out override feature
	0110	will automatically disable loopback time out. In other words, the loopback
		will not time out due to the current loopback time out option setting. As
		long as the units remain armed, the time out will remain disabled. When
		the units are disarmed, the loopback time out will revert to the previous
		loopback time out setting.
Span Power	6767	If the units are armed and 6767 is sent from the network or customer, the
Disable1, 2, 4	0110 0111 0110	H2TU-C will disable span power, turning off the H2TU-R. If the pattern is
	0111	sent from the network, the span power will be disabled as long 6767
		pattern is detected. Once the pattern is no longer received, the H2TU-C
		will reactivate span power. All units will then retrain and return to the
		disarmed and unlooped state. If the pattern is sent from the customer, the
		span power will only be disabled momentarily.

Note: All codes listed above must be sent for a minimum of 5 seconds in order for them to be detected and acted upon.

*If NIU is enabled, then the H2TU-R can be in network loopback when the H2TU-C loop up codes are sent.

1 The H2TU-C and H2TU-R individually detect and act upon in-band loopback control codes. Depending on which list number of H2TU-R is used with the Litespan H2TU-C, some of these control codes may not cause action (such as loop up, error injection, etc.) at the H2TU-R. Refer to the H2TU-R documentation for supported control codes.

2Units must be armed with 11000b or FF48h before this code will work.

3In order to behave like a NIU, the H2TU-R will not loop down from the network side with 9393h.

4 This code will be detected only if the units are armed OR if any loopbacks are active.

61221002L2-5B A-3