Maintenance Description
Issue 8.0 July 2002
9-61
Figure 9-19. Dual Ring Interworking Circuit (Node Failure in Other Ring)
When an unprotected incoming low-speed loss of signal (LOS) or OC-3 loss of
frame (LOF) is detected by the low-speed interface circuit pack at the primary
node (node 4), the low-speed interface circuit pack notifies the LNCTL circuit pack
via the BCLAN. The LNCTL circuit pack enters an automatic DRI switch request
and sends it to the board controller on the OC48 TRMTR (A/D) circuit pack. An
LOS condition on one or more of the DS3 or EC-1 inputs to a low-speed interface
circuit pack or an unprotected OC-3 LOS/LOF condition results in an automatic
DRI switch request for that STS-3 tributary or STS-1 tributary (Release 7 and
Primary Secondary
Low Speed
Interface
Node 4 Node 3
Other
Ring
Node
Other
Ring
Node
FT-2000
Line-Switched
Ring
Node 5
Node 1
Node 2
LOS
tpa 832824/01
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