Alcatel-Lucent 7750 SR OS - Automatic Protection Switching (APS); Figure 8: APS Protection (Single Chassis APS) and Switchover

Ports
Page 62 7750 SR OS Interface Configuration Guide
Automatic Protection Switching (APS)
APS is designed to protect SONET/SDH equipment from linear unidirectional or bidirectional
failures. The Network Elements (NEs) in a SONET/SDH network constantly monitor the health of
the network. When a failure is detected, the network proceeds through a coordinated predefined
sequence of steps to transfer (or switchover) live traffic to the backup facility (protection facility).
This happens very quickly to minimize lost traffic. Traffic remains on the protection facility until
the primary facility (working facility) fault is cleared, at which time the traffic may optionally be
reverted to the working facility.
Figure 8: APS Protection (Single Chassis APS) and Switchover
7750 SR 7750 SR
7750 SR 7750 SR
Working Facility
Protection Facility
data flow
7750 SR 7750 SR
Working Facility
Protection Facility
data flow
Working Facility
Protection Facility
data flow
1
2
3
7750 SR 7750 SR
7750 SR 7750 SR
Working Facility
Protection Facility
data flow
7750 SR 7750 SR
Working Facility
Protection Facility
data flow
Working Facility
Protection Facility
data flow
1
2
3