363-206-285
Applications
2-6 Issue 3 June 2001
OC-3 Path Switched Ring 2
The OC-3 path switched ring allows several remote sites to share the two-fiber
ring facility back to the CO (Figure 2-2). The DDM-2000 OC-3 Multiplexer
interfaces to the ring through the Main slots at the OC-3 rate and uses its
programmable VT1.5/STS-1 TSI capability. Path switching can be done on VT1.5
paths, STS-1 paths, or a mixture of these. Up to 84 DS1s, 3 DS3s, 3 EC-1s, or
equivalent combination can be added/dropped from the DDM-2000 OC-3
Multiplexer path switched ring at any node. Because of the ring's path protection
scheme, time slots must be reserved all the way around the ring for all ring traffic,
limiting the capacity of the ring to the OC-3 line rate. Like the DDM-2000 OC-3
add/drop topology, the TSI feature offers full flexibility in assigning signals
between low-speed DS1, DS3, or EC-1 ports, and the high-speed interface at
each node. The DDM-2000 OC-3 Multiplexer can easily adapt to unpredicted
growth at a ring node.
Extensive equipment reuse between DDM-2000 OC-3 terminal, add/drop, and
ring nodes offers a significant operational advantage. The DDM-2000 OC-3
Multiplexer ring shelf is the same shelf as used in terminal and add/drop
applications. Also, circuit packs can be retained when upgrading a linear network
toaring.
The ring topology routes traffic between a CO site and a set of RT sites, as in the
add/drop topology, while providing complete protection. In addition, only two
OLIUs are needed per DDM-2000 OC-3 Multiplexer, which provides a cost
savings over the add/drop topology. Traffic can also be routed between RT sites.
The ring can start with as few as two nodes and grow to support many nodes
through in-service node additions.
For protection against a CO failure, it may be desirable to include a second CO
node in the ring. This dual homing architecture allows all services to be routed to
the alternate CO while the first CO is out of service.
To Next Page
Loading...
Need help?
General
