363-206-305
Administration and Provisioning
8-40
Issue 3 June 2000
2000 nodes of an OC-3 ring, providing "ring-on-ring" architecture. Each OC-1 ring
so supported occupies up to 28 VT1.5 time slots on the OC-3 ring. When single-
homing is used, the OC-3 system passes the VT1.5 time slots between the OC-1
interfaces and OC-3 interfaces without terminating them or performing any path
protection switching on them. Up to six OC-1 rings can be supported by one DDM-
2000 OC-3 shelf in this way. Since the signals from the OC-1 ring(s) are sent as
two copies (one clockwise, the other counterclockwise) on the OC-3 ring, the OC-
3 ring capacity is limited to the OC-3 line rate (84 VT1.5 signals). So, although one
DDM-2000 OC-3 shelf can support up to six OC-1 rings, the full capacity of all six
OC-1 rings cannot be carried on the OC-3 ring.
The OC-1 lines between an OC-3 node and an OC-1 node behave like the OC-1
lines between the nodes on an OC-1 ring and do not perform line level protection
switching. Instead, the FiberReach shelves perform the normal path protection
switching functions.
Some points to note for this application are:
■
Single-homing can be thought of as a "ring on ring" with many of the
characteristics of a single ring.
■
Pass through cross-connections may be required at the VT level on both
the OC-1 and OC-3 rings.
■
The OC-1 ring can be composed of up to 28 VT1.5 signals from the OC-3
ring.
■
More DDM-2000 FiberReach wideband shelves could be added to the
OC-1 ring. A cross-connection from the OC-1 interface to a DS1 interface
would be required at one of the FiberReach wideband shelves on the OC-1
ring, and pass-through cross-connections would be required at all other
FiberReach wideband shelves on the OC-1 ring.
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