363-206-305
Maintenance Description
9-10
Issue 3 June 2000
Inservice Upgrades
9
All DDM-2000 FiberReach software releases support upgrades to future software
releases.
Maintenance Signaling
9
The DDM-2000 FiberReach Multiplexer provides maintenance signaling compliant
with the SONET standard (ANSI* T1.105).
*
The DDM-2000 FiberReach
Multiplexer generates and detects the following alarm indication signals (AISs),
which notify downstream equipment that a failure has been detected and alarmed
by some upstream equipment:
■
SONET line AIS
■
STS-1 path AIS
■
Virtual tributary (VT) path AIS
■
DS1 AIS (generated, not reported)
■
DS3 AIS.
The DDM-2000 FiberReach Multiplexer also generates and detects the following
signals, which notify upstream equipment of a failure detected downstream:
■
Line far-end-receive failure (FERF)
■
STS-1 path yellow and VT path yellow
■
STS-1 and VT path unequipped detection
■
An STS-1/VT AIS signal is inserted on paths that are not cross-connected.
The user can also provision a shelf to insert STS/VT1.5 unequipped in
place of AIS on a path that is not cross-connected.
Figure 9-3 is an example of the AIS, yellow, and FERF signals generated in
response to an unprotected incoming OC-1 line failure. In this figure, the labels on
the arrows pointing into the DDM-2000 FiberReach Multiplexer indicate the
maintenance signals and failure conditions recognized by the DDM-2000
FiberReach Multiplexer. The labels on the arrows pointing out of the DDM-2000
FiberReach Multiplexer indicate the signals generated by the DDM-2000
FiberReach Multiplexer in response to the indicated incoming signals or failure
conditions. The
Xs
indicate points of failure, either within the DDM-2000 OC-3
Multiplexer or in upstream equipment. Unlabeled arrows indicate normal
* Registered trademark of American National Standards Institute.
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