Eci Telecom XDM-100, General Description Manual

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System Design XDM® -100
4-4 ECI Telecom Ltd. Proprietary 417006-2005-013-A02
After the XDM-100 is switched on, a BIT program is automatically activated for
both the initialization and normal operation phases. The operator can stop its
execution (and also restart it) from eNM LightSoft™.
BIT testing covers general tests, including module presence tests and periodic sanity
checks of I/O module processors. It performs traffic path tests, MXC environment
tests, data tests, and detects traffic-affecting failures, as well as failures in other
system modules.
4.2 Timing and Synchronization
The XDM-100 features a TiMing Unit (TMU) residing in the MXC card that
provides highly redundant, high-quality system timing to all traffic modules and
functions.
The TMU unit and the internal and external timing paths are fully redundant. The
high-level distributed BIT mechanism ensures top performance and availability of
the synchronization subsystem. In case of hardware failure, the redundant
synchronization subsystem takes over the timing control with no traffic disruption.
In order to provide reliable timing, the XDM-100 provides multiple synchronization
reference options. Networkwide multiple XDM-100 systems provide a variety of
synchronization options.
Up to four of the following timing references can be monitored simultaneously by
each XDM-100 shelf:
♦
2 x 2 MHz external timing sources
♦
2 x 2 Mbps external timing sources
♦
2 x 1.5 Mbps (DS-1) external timing sources (BITS in)/SF, ESF, and
unframed
♦
STM-n/OC-n line timing from any SDH/SONET interface card
♦ Local interval clock
♦
Holdover mode
Each input timing source has its own 8 kHz frame timing, which is delivered to the
timing generator. The TMU selects one of the timing sources as a system reference.
The timing signal is received from each of the I/O modules and is routed to the
TMU through the timing reference bus. Any STM/OC line and E1 interface can be
selected as a reference source, transferring an 8 kHz timing signal to the TMU. The
external clock signal is routed directly to the clock unit, where the 8 kHz component
is extracted.