363-206-295
Applications
2-20 Issue 1 December 1997
The DDM-2000 drop-and-continue feature also finds an excellent application in
interconnecting two rings via an intermediate transport network. In the example
shown in Figure 2-12, DDM-2000 OC-3 Multiplexer access rings act as a DRI pair
via an FT-2000 OC-48 Lightwave System and DACS IV-2000 interoffice network.
The advantage of this network is the grooming for DRI traffic provided by the
DACS IV-2000. Both DDM-2000 OC-3 rings provide drop and continue at each of
their two duplicate COs. Both copies of the signal are transported as separate
tributaries through the interoffice network, and path switching is implemented at
the edges of the network. Signal redundancy is preserved on an end-to-end basis.
In offices where SONET interconnections are not available, DS3 interfaces can be
used between dual OC-12 offices. The DDM-2000 OC-12 Multiplexer also
supports DS3 DRI in addition to the EC-1 and OC-3 interfaces. In the event of an
incoming DS3 failure from the DSX-3, the OC-12 Multiplexer inserts an STS-1 AIS
signal into the STS-1 ring channel used by the DS3 to activate the downstream
STS path protection switch. It is recommended that SONET DRI interfaces (EC-1
or OC-3) be used if possible since the DS3 to STS-1 AIS translation feature is on
the OC-12 Multiplexers only (R5.1 and later).
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