Verilink 2048 (34-00179) Product Manual - Manual (Page 28)

4-8 Terminal Operation 2048 PMU/NTU
4.5.1 Test Loops
Loop status changes can be made only when the BERT
function is not in the active mode.
The PMU recognizes inband and FDL out-of-band loop-
back requests as well as local and remote network manage-
ment loopback testing configurations. The unit supports a
multitude of ways to test the service to and from the PMU.
The PMU has 2 loops, the line loopback and the payload
loopback. These are shown in Figure 4-3.
The PMU monitors network loopback commands and acti-
vates loops based upon their reception. Loops may be acti-
vated through the user interface via the supervisory port or
through a network manager. A loop may also be activated by
the front panel test switch.
Loop: This field activates any one of the following six loop
options by toggling the . The reference point for
the loopbacks is the ‘Target’ PMU selected in the Main
Menu. Some fields require that a ‘Keep Alive’ signal be
selected (‘AIS’ to pass all ones or ‘Pass’ to pass on the
selected data). The looping choices are as follows:
Far Net LLB: executes a line loopback at the far PMU.
Far Net PLB: executes a payload loopback at the far PMU.
Near Net LLB: executes a line loopback towards the far
PMU (Keep Alive selection required).
Near Net PLB: executes a payload loopback towards the far
PMU (Keep Alive selection required).
Near DTE LLB: executes a line loopback towards the near
DTE (Keep Alive selection required).
Unloop: Takes down the specified loop. The choices are the
same as those described in the above paragraphs.
4.5.2 BERT
Pattern: Specifies the pattern to be transmitted during a
test. Modifying this field will not cause the pattern to be
transmitted (refer to ‘Start Test’). BERT may also be acti-
vated via the front panel switch. The ‘
CLEAR ’ pattern
passes the received data through the unit (alarm detection
and reporting is disabled while the test is active). The
choices are
[QRSS] , [63] , [511] , [2047] , [2
15
] ,
[2
20
] , [2
23
] , [1:8] , [3:24] , [ ALT ], and [ CLEAR ].
Test Length: Defines the run-time of test pattern genera-
tion and error accumulation. The choices are
[Continu-
ous] , [15 min] , [30 min] , [60 min] , [24 Hour] .
Start Test: Pressing with the cursor on this field
starts the selected test pattern. ‘
TEST IN PROGRESS ’
appears once the test has started. To end the test, press
on ‘
STOP TEST ’.
Reset Errors: Pressing with the cursor on this
field causes the test error results to be cleared to zero.
The following fields are for display only. They reflect the
selected test parameters and the results of these tests only:
Pattern Sync: This field displays the current state of pat-
tern sync during a test. If no test is in progress, ‘
NO TEST ’
is displayed. If a test is active, but the receiver is not in pat-
tern sync, ‘
NO SYNC ’ is displayed. If the receiver is in pat-
tern sync, ‘ IN SYNC ’ is displayed.
Elapsed Time: Displays the amount of time elapsed since a
timed test began or, if completed, the total test time.
Bit Errors: Displays the total number of bit errors detected
since the test began or since error statistics were cleared (up
to a maximum number of 999,999).
Errored Seconds: This field displays the number of asyn-
chronous errored seconds that have been detected since the
test began or since error statistics were last cleared. This
parameter includes errored seconds and sync loss seconds.
% EFS: This ratio is derived from the number of error free
seconds divided by the number of seconds accumulated in
‘
Elapsed Time ’.
4.5.3 Line Fault and Loop Status
NET/DTE Status: These two fields display the fault status
of the network and the DTE. This status is an indicator of
current fault conditions. It does not indicate that alarm
thresholds have been exceeded. These status indications are
described in Table 4 -2.
Table 4-2 Status Indications
Near Loops: Displays the loop status of the ‘near’ element.
Far Loops: Displays the loop status of the ‘far’ element.
Status Description
------- No status is available
OK No errors are currently detected.
ERR Frame bit errors, CRC errors, or bipolar violations
are detected.
LOS A loss of signal condition exists.
OOF An out of frame condition exists.
RAI A remote alarm indication signal is being received
from the far end.
AIS An alarm indication signal is being received from
the far end.
UAS An unavailable signal state exists due to consecutive
severely errored seconds.