Product specifications

61181113L2-5A Issue 1, November 2003 A-3
Note: All codes listed above must be sent for a minimum of 5 seconds to be detected and acted upon
Table A-2. In-Band Addressable Loopback Codes
Function Code (Hex / Binary) Response
ARM (in-band) - also
known as 2-in-5 pattern
11000 (binary) The H2TU-R will loop back toward the network. No AIS or
errors will be sent as a result of this loopback. The H2TU-C
will arm.
Disarm (in-band) - also
known as 3-in-5 pattern
11100 (binary) The H2TU-C is removed from the armed state. If any of the
units are in loopback when the 11100 pattern is received, they
will loop down. The LBK LEDs will turn off on all units.
H2TU-C Loop Up
D3D3 or
1101 0011 1101 0011
If armed, the H2TU-C will loop back, 2 seconds of AIS (all
ones) will be transmitted, the looped data will be sent for 5
seconds, and then a burst of 231 logic (bit) errors will be
injected. The burst of 231 logic errors will continue every 20
seconds as long as the D3D3 pattern is detected. When the
pattern is removed, the unit will remain in loopback. If the
pattern is reinstated, the injection of 231 logic errors will
resume every 20 seconds.
Loop Down w/o Disarm 9393 or
1001 0011 1001 0011
When sent from the network, all units currently in loopback
will loop down. Armed units will not disarm.
Loopback Query
D5D5 or
1101 0101 1101 0101)
If the units are armed, and the H2TU-C or H2TU-R are in
network loopback, logic errors will be injected toward the
network to indicate a loopback is present toward the network.
The number of errors injected is determined by the 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
Loopback Time Out
Override
D5D6 or
1101 0101 1101 0110
If the units are armed or a unit is currently in loopback when
this pattern is sent from the network, the loopback time out
will be disabled. 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.
If any element is in network loopback a bit error confirmation
will be sent.
H2TU-C 231 bps
H2TU-R 20 bps
Span Power Disable
6767 or
0110 0111 0110 0111
If the units are armed and 6767 is sent from the network, the
H2TU-C will disable span power. If the pattern is sent from
the network, the span power will be disabled as long as 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.
H2TU-R Loopback C742
1100 0111 0100 0010
FDL, ESF only. When set from the network, an H2TU-R
network loopback is activated, and a 20-bit error confirmation
is sent. When set from the customer, an H2TU-R customer
loopback is activated with a 20-bit error confirmation.