363-206-305
Maintenance Description
Issue 3 June 2000
9-21
Status of ACTIVE LED on Rings
9
In all ring applications, ACTIVE LEDs on each Main OLIU are always lighted
because it is not known if a signal on that OLIU is currently being selected by a
far-end network element.
Low-Speed Equipment Protection
9
NOTE:
The protection module is determined by protection modules that are
shipped with each wideband shelf. The module is plugged into P2,
the protection bus connector located on the rear of the shelf. Along
with the modules, labels are shipped for identifying the low-speed
slots.
The DDM-2000 FiberReach Multiplexer offers 1x1 or 1x7 protection revertive
switching. In a 1x1 protection configuration, the eight slots are divided into four
low-speed groups — A, B, C, and D. The bottom four slots are the service A, B, C,
and D slots and the top four slots are the associated protection A, B, C, and D
slots. To prevent frequent protection switches caused by intermittent failures of a
DS1 or T1EXT circuit pack, the system provides an "automatic lock" feature. If four
automatic protection switches are done on the same DS1 or T1EXT circuit pack
within a 10-minute interval, traffic is automatically locked onto the protection circuit
pack and the automatic lock is reported as a minor alarm. The automatic lock can
be reset manually using the
switch-ls
command. It resets automatically at
midnight or if the affected DS1/T1EXT circuit pack is replaced. The DDM-2000
FiberReach Multiplexer also supports unprotected equipment configurations. DS1
and T1EXT circuit packs can be mixed in a 1x7 protection group but only one pack
type can be protected.
The DDM-2000 FiberReach Multiplexer provides very flexible low speed
equipment protection schemes to accommodate mixed services applications. The
schemes include 1X1 protected or 1x7 protected configurations, provisionable by
the user. Provisioning is done at installation using a low-speed protection
assembly on the backplane. The protection scheme can be changed (for example,
upgrading from 1x1 to 1x7) but must be done out-of-service.
Synchronization Reference Protection
9
For DDM-2000 FiberReach, the synchronization references are 1
×
1 protected. If
neither reference is available, the system automatically switches to "holdover"
timing mode. The system uses synchronization messaging to determine the
quality of the loop timing references by reading the synchronization messages in
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