Lucent Technologies DDM-2000 OC-3, User & Service Manual

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363-206-285
Applications
Issue 3 June 2001 2-19
channel transport in a campus or other self-contained environment where there is
no need for the additional capacity and flexibility of an OC-3 backbone network.
Folded Ring 2
DDM-2000 OC-3 and OC-12 rings offer several benefits in addition to service
assurance. Economically, a ring network minimizes overall network cost by
requiring fewer optical transmit/receive units than a comparable linear add/drop
network. Operationally, a ring network provides significant flexibility to increase
bandwidth at existing nodes and to add new nodes at locations where
unanticipated bandwidth is required.
These benefits make rings highly desirable even when fiber route diversity is not
available. When route diversity is not available on part or all of the ring, ring
technology can be used to support split and tapered feeder routes to derive
economic benefits, provide bandwidth flexibility, ease the process of adding and
deleting nodes and supply survivability against single-node failures.
When route diversity is not available or fiber cable cuts are not a driving concern,
the two-fiber path switched ring feature can be applied in a "folded" (a folded ring
is a single path ring) configuration (Figure 2-12). This use of DDM-2000 OC-3,
OC-12, and
SLC -2000 access resource manager (ARM) path switched rings
applies in particular to hubbing and linear topologies where there is no return path
from the end remote site to the CO. While a complete cut through the fiber cable
cannot be protected, single-node equipment failures are still protected.
Furthermore, a two-fiber ring ARM uses only one optical transmitter/receiver in
each direction (two per remote shelf), in contrast to a 1+1 line protection
arrangement that requires four optical transmitter/receivers per remote shelf.
Thus the ring configuration reduces equipment costs, a benefit independent of its
survivability advantage. The ring topology also makes node addition/deletion
straightforward.