Administration and Provisioning
8-24 Issue 8.0 July 2002
Limited STS-1 Cross-Connections 8
In Releases 5 and 6 only, the FT-2000 OC-48 Add/Drop-Rings Terminal supports
limited STS-1 cross-connections with external loopback cables and an STS-1
squelch map across an STS-3 signal. (Limited STS-1 cross-connections across
an STS-3 signal are not supported in Release 7 and later releases.) External
loopback cables are required when all three STS-1 tributaries from the same low
speed interface circuit pack (DS3 or STS1E) are not being added or dropped.
Each FT-2000 OC-48 Add/Drop-Rings Terminal in a ring network also maintains
an STS-1 squelch map that allows each STS-1 tributary to have its own source
node and destination node.
The source node and destination node information in the STS-1 squelch map
enables switching nodes to squelch STS-1 tributaries that are looped back
(through cabled) based on the source and destination nodes. Thus, if a node that
has through-cabled STS-1 tributaries becomes isolated from the source and
destination nodes of the through traffic due to a node failure or multiple line
failures, only the add/drop traffic at the isolated node is squelched. The
through-cabled STS-1 tributaries are protected using 2-fiber ring protection
switching if the source and destination nodes are not isolated from each other. In
releases prior to Release 5, through-cabled STS-1 tributaries were not protected
against intermediate node failures.
Limited STS-1 cross-connections are established by entering a 1-way or 2-way
cross-connection between a service low speed interface slot and a service STS-3
tributary of OC-48 high speed line 1E (or 1W) and another cross-connection
between a second service low speed interface slot and the STS-3 tributary of
OC-48 high speed line 1W (or 1E). The two service low speed interface slots must
be equipped with the same type of low speed interface circuit pack (DS3 or
STS1E). The STS-1 tributaries (DS3 or EC-1 signals) to be dropped and/or added
are connected to a DSX-3 panel, STSX-1 panel, DACS-III 2000 Cross-Connect
System, or DACS-IV 2000 Cross-Connect System. The through-cabled STS-1
tributaries are looped back from the output(s) of the circuit pack in the first slot to
the input(s) of the circuit pack in the second slot.
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