Product Overview
System Architecture
32
SSU-2000 User’s Guide
12713020-002-2 Revision D – April 2004
After you select the reference switching mode, the Input module reads and
processes the Priority level and PQL value to determine the traceability of inputs.
This traceability information is then used by the Clock modules in selecting a
reference signal and for embedding the SSM into the outputs.
If you select
Priority
mode, the SSU-2000 selects the input reference with the
highest user-defined Priority setting; if all inputs have the same Priority level, then
the input with the highest PQL (quality level, SSM) is used.
If you select
PQL
mode, the SSU-2000 selects the input reference with the highest
assigned PQL level or associated SSM; if all inputs have the same PQL/SSM value,
then the input with the highest Priority levels is used. In either case, error codes
such as Loss of Signal (LOS), Out of Frame (OOF), MTIE, TDEV, and Phase
performance data collected at the inputs are used to disqualify inputs (prevent input
selection) based on user defined thresholds.
In either mode, when the Priority and PQL values are equal for each input, the
physical location of the Input module determines the priority for selecting the input
reference. Port 1 on the Input module in the leftmost slot has the highest priority; the
priority decreases to port 1 on the Input module in the rightmost slot. Port 2 on the
module in the leftmost slot has the next lower priority, decreasing to Port 2 on the
Input module in the rightmost slot. Port 3 on the module in the leftmost slot has the
next lower priority, and Port 3 on the module in the rightmost slot has the lowest
priority.
If the Input module is configured for provisioned mode, it reports the user-assigned
SSM. If it is configured for automatic mode, the Input module uses the most recent
valid SSM. If a valid SSM is not received, the module uses the user-assigned SSM.
Setting an Input Alarm Strategy
You can provision the SSU-2000 to elevate input alarms to the next higher level
after a specified amount of time. You can also specify that an alarm clears
automatically after a specified period of time without the alarm condition. For more
information on alarms, see
Bypass Clock (Clock C)
In the event that both Clock modules fail, an input connected to a D1, E1, or
Composite Clock Input module can serve as the system reference. The input must
be a valid reference, and it must have a Priority setting. When the Bypass clock is
the active reference, then the output signal is not filtered and any wander or jitter on
the input signal appears on the outputs. The Bypass clock is intended only for
short-term use; you should resolve the failures on the Clock modules as quickly as
possible.
Содержание SDU-2000
Страница 12: ...12 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 18: ...18 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 142: ...Clock Module Reference Data Communications Module 142 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 172: ...Input Module Reference Data Input Adapter Panels 172 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 222: ...Output Module Reference Data Output Adapter Panels 222 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 390: ...SNMP Protocol 390 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 420: ...I O Connector Grounding 420 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 434: ...User Changes to Factory Defaults 434 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...