Administration and Provisioning
Issue 8.0 July 2002
8-39
high-speed line 1E or 1W. In Release 7 and later releases 1-way, 1-way-DRI, and
2-way cross-connections are possible between any service low speed port and
any protection STS-1 tributary of OC-48 high speed line 1E and 1W.
Cross-connections are also possible between any protection STS-3 or STS-1
(Release 7 and later) tributary of OC-48 high-speed line 1E or 1W and the
same-numbered protection STS-3 or STS-1 tributary of the other OC-48
high-speed line.
For example, Figure 8-14 shows service low-speed interface slot 4B
cross-connected to protection STS-3 tributary 10 of OC-48 high-speed line 1E
(2-way) and protection STS-3 tributary 14 of OC-48 high-speed line 1W
cross-connected to protection STS-3 tributary 14 of OC-48 high-speed line 1E
(2-way).
FT-2000 ADR Release 7.0 and Earlier Releases 8
Extra traffic is preempted if a 2-fiber ring protection switch occurs. In 2-fiber ring
protection switching, the protection STS-3 tributaries of OC-48 high speed line 1E
protect the service STS-3 tributaries of OC-48 high speed line 1W, and the
protection STS-3 tributaries of OC-48 high speed line 1W protect the service
STS-3 tributaries of OC-48 high speed line 1E. For more information about 2-fiber
ring protection switching, refer to Volume I, Section 9, "Maintenance Description."
FT-2000 ADR Release 7.1 and later Releases 8
With R7.1 those tributaries on the protection fiber that are used to carry extra
traffic are designated as either “Preemptible Protection Access” or
“Non-Preemptible Protection Access (NPPA).”
The extra traffic carried by non-preemptible tributaries is not dropped (preempted)
by any ring loopback protection switch. Since protection switching in a ring is
always bidirectional there will always be two unprotected tributaries for each
tributary of NPPA traffic carried. One on the service fiber and the other on the
protection fiber.
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