Applications
Issue 8.0 July 2002
2-23
The two-fiber ring is used to transport the ATM traffic from the optical hubs to the
ATM switches at CO 3 and CO 4. The two-fiber ring is also used to interconnect
the ATM switches. The STS-3c payload is routed through the OC-48 ring using
STS-3 cross-connections (Release 5 and later) or STS-1 (Release 7 and later)
cross-connections. (The three STS-1 cross-connections must be to the same
STS-3 tributary.)
!
CAUTION:
Exercise caution when using STS-1 cross-connections to provision
STS-3c/STS-12c circuits. It is possible to provision circuits with STS-1
cross-connections that do not properly carry STS-3c/STS-12c signals and
are not reported or alarmed. For example, if the second and third STS-1
signals in an STS-3c signal are transposed at an add cross-connection or at
a drop cross-connection, the resulting STS-3c signal will be corrupted but
no conditions are reported or alarmed.
For more information about the STS-3c/STS-12c concatenated signals, refer to
the "Concatenated Mode" part of Appendix A, "A SONET Overview." For more
information about cross-connections, refer to Volume I, Section 8, "Administration
and Provisioning."
The FT-2000 OC-48 Add/Drop-Rings Terminal equipped with OC-3 low-speed
interfaces can also be provisioned to transport SONET STS-3 and STS-3c
payloads or synchronous digital hierarchy (SDH) STM-1 AU-4 mapped payloads.
This allows a direct interface to SDH equipment over an STM-1 optical
connection. The OC3 circuit pack can automatically support transport of STS-3,
STS-3c, or STM-1 signals carrying AU-4 mapped signals. For more information
about provisioning an OC-3 low-speed interface, refer to the information
describing the CONFIGURATION-Set-OC3 input in Volume I, Section 8,
"Administration and Provisioning."
Similarly, and in summary, the OC-12 low-speed interface can transport a single
SONET STS-12c signal, a combination of STS-1 and STS-3c signals, or an SDH
type STM-4 signal.
In Release 6 and later releases, the FT-2000 OC-48 Add/Drop-Rings Terminal
provides single-ended operation capabilities through the OC-3 DCC. For more
information about the single-ended operation capabilities, refer to the “Operations
Interworking” application in this section. For more information about operations
interworking between the FT-2000 OC-48 Lightwave System and the DDM-2000
Multiplexers, refer to 824-102-147,
2000 Product Family Operations Interworking
Guide
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