Verilink Access Manager 2000 (896-502037-001) Product Manual - Manual (Page 312)

Monitoring and Troubleshooting Access Manager
8-42 Access Manager 2000 User Manual
List 1, 1/A, and 4016 List 1. Note that Access Manager blocks
transmission of the inband loop-up and loop-down codes from the far-end
CSU to the near-end CSU.
The following LEDs light up on the CSUs (NCCs (CCCs) and TACs)
during an LLB (SPAN is equivalent to network [NET]):
If the LLB at the far end is activated by sending the inband loopback code
from the near-end CSU, the near-end 551VST List 1/A, List 2, and 4016
List 2 activate their network (NET) Far-End Looped LEDs when inband
loop-up code is received back at the near-end CSU. This indicates that the
far-end CSU or network is looped back to the near-end CSU.
Note: Releasing the far-end LLB by any method except sending an
inband loop-down code does not extinguish the span (i.e.,
network) far-end looped LED. If a far-end LLB is activated by a
Data Link message, the far-end CSU will not respond to an
inband loop down code
RLB - Repeater Loopback
When a repeater loopback (RLB) is in effect, the signal from the EQPT is
looped back to the EQPT through the CSU repeater.
Since the looped signal passes through all CSU circuitry except the
network input and output transformers, the RLB EQPT is useful in testing
the operation of the CSU locally. The CSU always passes the EQPT
signal intact to the network during RLB.
Equipment Message
551 VST List 1
551 VST List 1/A SPAN INBAND LOOPED
4016 List 1 SPAN INBAND LOOPED
551 VST List 1/B
551 VST List 2 SPAN NEAR END LOOPED
4016 List 2 SPAN LOOPED
4016-R SPAN LOOPED
NCC or TAC NET LED flashes amber