363-206-285
Administration and Provisioning
Issue 3 June 2001
8-57
application, the TSI can change in each extension. The same VTG/VT will be
used but the STS can change.
The OC-3 (VT level) cross-connections are:
â– At CO-1: a-1-4:m-3-2-1
The first VT in the second VTG is assigned between CO and CO-1. This
slot will be used to transport the DS1 that will terminate on port a-1-4.
â– At RT1-1: b-2-1:m-1-2-1
The above DS1 will leave the system from port b-2-1 at RT1-1. The VTG/
VT slot (-2-1) is set by the cross-connection at CO-1. Because OC-12 STS
mb-1 is dropped to the first STS in this OC-3 extension (m-1), port b-2-1 is
cross-connected to m-1-2-1.
â– At RT2-2: m-2-2-1:m-2-2-1
At RT2, time slot mb-1 is dropped to the second STS going to RT2-2 (m-2).
The VT/VTG assignment remains -2-1. A VT pass-through cross-
connection is needed to enable future DS1s to be dropped at RT2-2. If
drops will never be needed, STS pass-through cross-connections can be
used.
â– RT3 is an OC-3 shelf equipped with OC-12 optics. The 24G-U OLIUs
provide the ability to drop up to any three of the 12 STS-1s at this node.
The remaining STS-1s continue on the OC-12 ring.
With these cross-connections, DS1s originating at any of the three OC-3 nodes
can be terminated at any one of the others with VT cross-connections at those
nodes only. The STS "pipe" is in place with the OC-12 cross-connections. As was
the case with the example DS1, two VT drop cross-connections and two pass-
through cross-connections are needed.
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