Verilink Access Manager 2000 (896-502037-001) Product Manual - Manual (Page 313)

Activating/Deactivating CSU loopbacks
Access Manager 2000 User Manual 8-43
After an operator-defined time, the RLB is deactivated by the RLB timer.
This prevents lockout during far-end-initiated loopback via the ESF Data
Link. The default value for this time-out option varies depending on the
type of CSU used. The RLB time-out is in effect regardless of whether
the loopback to the near-end or to the far-end was initiated locally at the
CSU or remotely via Access Manager.
CAUTION
Performing a far-end RLB locks out any messages from the ESF
Facility Data Link.
The CSU front panel EQPT LOOPED LED illuminates while the RLB is
in effect. For an NCC 2020, CCC 1020, TAC 2010, and TAC 1010, the
EQPT LED flashes amber during an RLB. The 551VST List 1 or 1/A and
4016 List 1 do not have the RLB and respond with the error message,
REQUEST REJECTED BY NODE OF CIRCUIT ELEMEN .
ELB - Equipment Loopback
When an equipment loopback (ELB) is in effect, the signal from the
equipment is looped back to the equipment on the EQPT side of the CSU.
Since the looped signal does not pass through the CSU circuitry, the ELB
is useful in testing the operation and connection of the EQPT. Most CSUs
can be configured to pass the EQPT signal intact to the network or to send
unframed All-ONEs (i.e., AIS) to the network during loopback.
The EQPT Looped LED on the CSU front panel lights while the ELB is
in effect. For an NCC 2020, CCC 1020, TAC 2010, and TAC 1010, the
STATUS LED flashes amber during an ELB.
Before setting up any loopbacks, you need to verify a timing issue if the
CSU is used with a DIU. You must determine the appropriate CSU timing
for that loopback. For example, avoid tests with no timing source: when
an LLB is set and the network does not supply timing, then NET timing
the unlooped CSU is invalid and introduces errors in the test.
To set loopbacks:
!
Procedures for
loopbacks