Administration and Provisioning
Issue 8.0 July 2002
8-21
In Release 5 and later releases, 1-way-DRI cross-connections are made from any
service low-speed interface slot and the companion low-speed interface slot (for
example, 2A and 2B) when the slot pair is provisioned for the OC-3 1+1 protected
mode. For example, Figure 8-5 shows incoming service STS-3 tributary 6 of
OC-48 high-speed line 1E cross-connected to outgoing service STS-3 tributary 6
of OC-48 high-speed line 1W. Service low-speed interface slot pair 4A and 4B is
also cross-connected to outgoing service STS-3 tributary 6 of OC-48 high-speed
line 1W.
A single input enters an active and standby add cross-connection from the service
low-speed interface slot pair to a service STS-3 tributary and a standby through
cross-connection for the same STS-3 tributary.
The active add cross-connection carries traffic during normal conditions. In
Release 4.1 and later releases, if an incoming DS3 or EC-1 loss-of-signal
condition is detected by the low-speed interface circuit pack, the through
cross-connection becomes active and the add cross-connection becomes
standby. In Release 5 and later releases, an unprotected incoming OC-3
loss-of-signal or loss-of-frame condition also causes the through cross-connection
to become active and the add cross-connection to become standby.
For Release 7.0 and prior releases, when the LOS, LOP, LOF, or Line AIS
condition clears, traffic does not automatically switch (revert) to the add
cross-connection. A reset
must
be performed using the
FAULT-Switch-Path-STS3 input to switch the traffic back to the add
cross-connection.
Release 7.1.0 and later releases provide revertive DRI and automatically switch
back to the service fiber.
For more information about the dual ring interworking (DRI) application, refer to
Volume I, Section 2, "Applications." For more information about DRI protection
switching, refer to Volume I, Section 9, "Maintenance Description."
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