Verilink QUAD T1 (880-503345-001) Product Manual - Manual (Page 44)

Diagnostics and Alarms
5-2 Verilink QUAD T1 User Manual
Be sure to stop all tests and de-activate all loopbacks when testing
is completed.
NOTE: Line loopbacks initiated via an FDL message to a remote node
are inhibited if the T1 line being used is set to enable inband
management. This is done to prevent an unintended loss of
communication when a T1 being used for management is
placed into a loopback condition.
The indicators and options on the Diagnostics Menu are listed in
Table 5-1 .
Table 5-1 Diagnostics Menu Options
Item Description
loop type Indicates what type of loop is currently in effect for the port.
test pattern Indicates which test pattern, or none, is being transmitted by the port.
BERT count Indicates the number of test errors since they were last reset.
BERT overflow Indicates the number of times the error counter above has overflowed. The
maximum is 20,000,000. Reset the error counter when this value is reached.
BERT rate Indicates the error rate computed by bit errors divided by total test bits received.
Expressed as a ratio such as 1 in 10 to the sixth power.
Ln) line loop A loopback in the local QUAD T1 module that faces the network. Traffic that is
received from the network is sent back to the network. Tests a minimum portion of
the local QUAD T1 module. Best used to test the T1 facility from a remote test
point. This test is frequently used by network service providers.
Pn) payload loop A loopback in the local QUAD T1 module that faces the network. With this loopback
in place, more of the local QUAD T1 module is tested. If payload loop fails while
line loop passes, verify that the timing options are set correctly.
Rn) local loop A loopback in the local QUAD T1 module that faces the local QUAD T1 module.
Traffic that would otherwise be sent out to the network is returned to its source. If
a local loop fails, there is a local configuration or hardware problem. The port
sends AIS (Alarm Indication Signal—a pattern of unframed all ones) toward the
network during a local loop.
Cn) send LLB 62411 Sends a request for a loopback in the DS0 payload using a pattern defined in
Bellcore specification 62411. Produces a line loopback in the remote CSU that faces
the local QUAD T1 module. This loopback should work on a T1 facility which
passes through a DACS (Digital Access and Cross-connect System).
An) send LLB BOP Sends a request for a loopback in the 4K FDL (Facilities Data Link) portion of ESF
framing. Produces a line loopback in the remote CSU that faces the local QUAD T1
module. This loopback will not work on a T1 facility which passes through a DACS
unless the FDL portion of the ESF framing is mapped through the DACS.
NOTE: If Performance Response Messages (PRMs) are enabled in the FDL
configuration menu, remote loopbacks may terminate after only a
few seconds. This happens because the ANSI T1.403 specification
indicates that PRM messages should terminate a loopback. To avoid
this problem, turn off PRMs before sending a request for a far-end
Line Loopback (LLB) or Payload Loopback (PLB).