Basic Node
3.7.2.1.6 Power
This block interfaces the Power bus and provides secondary voltages for the
unit. All plug-in units have a standard power module providing electronic soft
start and short circuit protection, filter function, low voltage protection, DC/DC
converter and a pre-charge function.
3.7.2.2 Fault Management
The AAU supports the handling of F4/F5 O&M functions for Fault Management
(FM), according to ITU-T I.610. The following FM indications are used:
• Alarm Indication Signal (AIS), for reporting defect indications in the forward
direction. The AIS cells at VP or VC level are sent upon one of the following
conditions:
− Receiving transmission path defect indications from the physical layer
− Detecting Loss of Cell Delineation (LCD)
− Detecting Loss of Continuity (LOC)
• Remote Defect Indication (RDI), for reporting remote defect indications
in the backward direction. RDI is sent to the far-end from a VPC/VCC
endpoint as soon as it has detected an AIS condition.
• Loop Back (LB), allowing for “operations related” information to be inserted
at one location along a VPC/VCC and returned (or looped back) at a
different location, without having to take the connection out-of-service.
This capability is performed by inserting an LB cell at an accessible point
along the VPC/VCC without disrupting the sequence of user cells while
minimizing the user cells transfer delay. This cell is looped back at a
downstream point according to the information contained in its information
field. It is used mainly for:
− On-demand connectivity monitoring
− Fault localization
− Pre-service connectivity verification
• The AAU is transparent to Continuity Check (CC) cells, for monitoring
continuity and detection of ATM layer defects in real time.
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4/1555-CSH 109 32/1-V1 Uen B 2007-09-14
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