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

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363-206-285
Transmission and Synchronization Interfaces
5-16 Issue 3 June 2001
Ring Interfaces 5
Ring interfaces can be used in single or dual homing applications. This part
describes the following ring interfaces:
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OC-3/OC-12 ring (0x1) single homing
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OC-3/OC-12 ring (0x1) dual homing
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OC-3/OC-12 linear (1+1) optical extensions
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OC-3/OC-1 ring (0x1) single homing
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OC-3/OC-1 ring (0x1) dual homing.
OC-3/OC-12 Ring (0x1) 5
The DDM-2000 OC-12 ring supports (0x1) OC-3/IS-3 interfaces in its function unit
slots. These interfaces must be provisioned as 0x1 in either single homing or dual
homing applications (see Figure 5-9 and Figure 5-10). Signals pass through the
DDM-2000 OC-12 transport ring and exit to the DDM-2000 OC-3 ring. OC-12
function unit slot FN(x)-1 is connected to OC-3 main-1 and OC-12 function unit
slot FN(x)-2 is connected to OC-3 main-2. Switching is not done on the
DDM-2000 OC-12 Multiplexer on these lines, or paths on these lines; rather VT1.5
or STS-1 level path switching is done on the DDM-2000 OC-3 Multiplexer. This
allows DDM-2000 OC-3 nodes running ring software to interface with DDM-2000
nodes of an OC-12 ring in such a way as to provide ring-on-ring architecture.
Each OC-3 ring so supported occupies up to three STS-1 time slots on the OC-12
ring. Each OC-12 node can provision the same STS-1 time slots as other OC-12
nodes to drop to the OC-3 shelf (to share STS-1s among several OC-3 shelves)
or the OC-12 node can provision different STS-1s at different sites. The OC-12
ring passes the contents of these STS-1 time slots between the low-speed OC-3/
IS-3 lines and OC-12 high-speed lines without terminating them or performing any
path protection switching on them. Up to four OC-3 rings can be supported in this
fashion by an OC-12 ring to maximize the OC-12 bandwidth utilization. This
allows access to any and all VT1.5 signals at an OC-12 site.
The OC-3/IS-3 lines between an OC-12 node and an OC-3 node connected in a
ring (0x1) fashion, behave like the OC-3 lines between the nodes on an OC-3 ring
and do not perform line level protection switching. Instead, the OC-3 shelves
perform the normal path protection switching functions.