Maintenance Description
9-62 Issue 8.0 July 2002
later). A DRI protection switch will not occur in response to any other low-speed
line failure (for example, AIS or signal degrade).
The board controller on the OC48 TRMTR (A/D) circuit pack activates the selector
circuitry to choose the incoming STS-3 tributary or STS-1 tributary from the
secondary node. This causes the through cross-connection at the primary node to
switch to the active state and the add cross-connection to switch to the standby
state. This completes the DRI circuit through the secondary node.
An automatic or manual DRI protection switch request will complete successfully
even if there is a corresponding incoming loss of signal condition at the secondary
node (node 3). The primary node does not monitor the condition of the incoming
low-speed signal at the secondary node.
The DRI protection switch will not work if the DRI circuit is being used for extra
traffic and a high-speed protection switch is active.
Figure 9-20 shows a dual ring interworking application with a primary node failure.
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