Specifications

7-19
Cisco MGX 8850 (PXM45) and MGX 8950 Software Configuration Guide
Release 3, Part Number 78-14788-01 Rev. C0, January 2004
Chapter 7 Switch Operating Procedures
Managing Redundant APS Lines
Figure 7-4 Crossed APS Configuration
Line failures are always detected at the receive end of the line. This is where a switchover occurs when
a failure is detected. Two different types of switchovers can occur, depending on whether the APS was
configured as unidirectional or bidirectional in the cnfapsln command:
• When a failure occurs on a line configured for unidirectional switching, the switch changes lines at
the receive end only. A switchover is not necessary at the transmit end because the transmitting back
cards send signals on both lines in the 1 +1 APS configuration.
• When a failure occurs on a line configured for bidirectional switching, a switchover occurs at both
ends of the line.
If the status of the standby line is good, a switchover from the failed active line to the standby is
automatic.
Enter the cnfapsln command to enable an automatic switchover back to the working line after it recovers
from a failure, as shown in the following example:
M8850_LA.1.AXSM.a > cnfapsln -w 1.1.1 -rv 2
Table 7-4 describes the configurable parameters for the cnfapsln command.
AXSM front card
Secondary card
Standby card
AXSM front card
Primary card
Active card
Remote node
Protection line
Stendby line
Signal
Backcard
Backcard
Backcard
APS connector
Tx 2
22
Tx RxRx
2
1
AXSM front card
Secondary card
Active card
AXSM front card
Primary card
Standby card
Local node
APS connector
Tx
3
Backcard
Tx RxRx
45
6
6
3
Working line
Active line
11
Backcard
Backcard
Backcard
70055
Physical line
BackcardBackcard