VeEX VePAL TX300M, Руководство пользователя

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10.2.7 APS Tasks
10.2.7.1 APS Timing
This function measures the Automatic Protection Switching (APS) limits of the network. APS applies only to the Multiplex sections
of a SONET network and enables network elements to re-route traffic to a backup circuit in the event of network failure or
problems. The protection mechanism is coordinated by the K1 and K2 bytes in the Multiplexer Section Overhead.
APS Standards
The principles and protocols of APS in SONET networks are defined in ITU-T G.783 and G.841 and Bellcore GR-253
recommendations for Linear and Ring network architectures respectively. According to these recommendations, the re-
routing of the signal has to occur within 50ms. Protection switching is initiated as a result of one of the following conditions:
“Hard” Failure (SF) condition – Loss of Signal (LOS), MS-AIS, BER >1 x 10
-3
.
“Soft” Failure (SD) condition – Signal degradation when BER exceeds a predetermined threshold. Normally over a
provisioned range of 1 x 10
-5
to 1 x 10
-9
.
Tap the APS Testing icon to display the APS testing screens shown below.
Sensor:
Select the trigger that will initiate the APS measurement.
The selections are: LOS, LOF, SONET FAS, B1, B2, B3, AIS-L, RDI-L, REI-L, AIS-P, LOP-P, RDI-P, REI-P, AIS-
V, 2M-LOF, 2M-AIS, LSS and TSE (bit errors)
Switch Time Limit:
Configurable in the range from 15ms to 200ms.
Typically 50ms according to ITU-T recommendations.
Gate Time
: Configurable in the range from 50ms to 4 seconds.
Used to measure total service disruption when multiple switches or micro interrupts occur.
Repeat
: ON/OFF
Configurable to measure on a continuous basis.
Start
: Press to begin the test.
APS Timing Setup
TX300S_e-manual_D07-00-064P_RevA00