Maintenance Description
Issue 8.0 July 2002
9-55
Optical Low Speed Protection Switching
Example 9
Figure 9-16 shows two OC-12 lines (only one direction of transmission is shown)
and two FT-2000 OC-48 Add/Drop-Rings Terminals. The FT-2000 OC-48
Add/Drop-Rings Terminal at Office A transmits service traffic on both OC-12 lines.
The FT-2000 OC-48 Add/Drop-Rings Terminal at Office B monitors the two OC-12
lines independently and chooses one OC-12 line as the active line and the other
OC-12 line as the standby line.
Figure 9-16. 1+1 OC-12 Line (Normal Transmission)
Figure 9-14 shows two OC-12 lines (only one direction of transmission is shown)
and two FT-2000 OC-48 Add/Drop-Rings Terminals when a fiber cut occurs on the
active OC-12 line. Automatic 1+1 OC-12 line protection switching occurs in
response to a signal fail or signal degrade condition on the incoming OC-12
signal.
Optical low-speed protection switching is only performed in the add (OC-12 to
OC-48) direction by the FT-2000 OC-48 Add/Drop-Rings Terminal at Office B. The
board controller on the OC48 TRMTR circuit pack activates the selector circuitry
to choose the 155 Mb/s or 622 Mb/s signal from the standby OC12 (1.3 STD) or
OC12 (1.3 STD) circuit pack. The standby OC12 (1.3 STD) circuit pack becomes
the new active OC12 (1.3 STD) circuit pack. The original active OC-12 line
becomes the standby OC-12 line.
OC-12
Standby
Active
OC12
Office A
Office B
OC48 TRMTR
OC12
OC48 RCVR
OC12
OC12
nc-ft2000-037
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