Maintenance Description
Issue 8.0 July 2002
9-37
■ The LNCTL circuit pack transmits a request to preempt any extra traffic to
the board controllers of the transmission circuit packs. After extra traffic is
preempted, through cross-connections are established for the protection
STS-3 tributaries. Through cross-connections are established using the C
bus between the west OC48 RCVR (A/D) and east OC48 TRMTR (A/D)
circuit packs and the east OC48 RCVR (A/D) and west OC48 TRMTR
(A/D) circuit packs. Figure 9-7 shows that extra traffic has been preempted
and through cross-connections have been established for the protection
STS-3 tributaries at nodes 2 and 3. The add/drop cross-connections to the
service STS-3 tributaries are not affected.
■ The west OC48 TRMTR (A/D) circuit pack passes through the switch
request to the other nodes using the APS channel on OC-48 high-speed
line 1W.
At node 1, the following occurs:
■ The east OC48 RCVR (A/D) circuit pack receives the switch request via the
APS channel and notifies the LNCTL circuit pack.
■ The LNCTL circuit pack transmits a protection switch request to the board
controllers on all the circuit packs and notifies the east OC48 TRMTR
(A/D) circuit pack.
■ The low-speed interface circuit packs that add/drop traffic to/from the
failure, and the east OC48 TRMTR (A/D) and OC48 RCVR (A/D) circuit
packs switch traffic to the protection STS-3 tributaries of OC-48 high-speed
line 1E. An add/drop cross-connection is established between the affected
low-speed interface slot and the protection STS-3 tributaries of OC-48
high-speed line 1E. The add/drop cross-connection is established using
the A bus between the affected low-speed interface circuit pack and the
east OC48 TRMTR (A/D) and OC48 RCVR (A/D) circuit packs. Figure 9-7
shows low-speed interface slot 3A cross-connected to the protection
STS-3 tributary 11 of OC-48 high-speed line 1E.
■ The east OC48 TRMTR (A/D) and OC48 RCVR (A/D) circuit packs loop
back all the through STS-3 tributaries transmitted toward the failure from
the service STS-3 tributaries to the protection STS-3 tributaries of OC-48
high-speed line 1E. The loopback is established using the B bus between
the east OC48 TRMTR (A/D) and OC48 RCVR (A/D) circuit packs.
Figure 9-7 shows extra traffic is preempted and service STS-3 tributary 6 of
OC-48 high-speed line 1E is looped back to protection STS-3 tributary 14.
(Table 9-4 shows the mapping between the service STS-3 tributaries and
their protection STS-3 tributaries.)
■ The east OC48 TRMTR (A/D) circuit pack also returns a switch
confirmation to node 0 using the APS channel on OC-48 high-speed line
1E.
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