Alcatel-Lucent 7750 Configuration Manual page 87

in each MDA with a logical next-hop index. This next hop-index identifies the actual next-hop
information used to direct traffic to the APS working circuit on IOM-1 / MDA-1.
All Flexible Fast-Path complexes in each MDA are also programmed with next hop information
used to direct traffic to the APS protect circuit on IOM-2/MDA-1. When the transmitted data
needs to be switched from the working to the protect circuit, only the relevant next hop indexes
need to be changed to the pre-programmed next-hop information for the protect circuit on IOM-2 /
MDA-1.
Although the control CFM/CPM on the SF/CPM blade initiates the changeover between the
working to protect circuit, the changeover is transparent to the upper layer protocols and service
layers that the switchover occurs.
Physical link monitoring of the link is performed by the CPU on the relevant IOM for both
working and protect circuits.
Switchover Process for Received Data
The Flexible Fast-Path complexes for both working and protect circuits are programmed to
process ingress. The inactive (protect) circuit however is programmed to ignore all packet data. To
perform the switchover from working circuit to the protect circuit the Flexible Fast-Path complex
for the working circuit is set to ignore all data while the Flexible Fast-Path complex of the protect
circuit will be changed to accept data.
The ADM or compatible head-end transmits a valid data signal to both the working and protection
circuits. The signal on the protect line will be ignored until the working circuit fails or degrades to
the degree that requires a switchover to the protect circuit. When the switchover occurs all
services including all their QoS and filter policies are activated on the protection circuit.
APS User-Initiated Requests
The following sections describe APS user-initiated requests.
Lockout Protection
The lockout of protection disables the use of the protection line. Since the
tools>perform>aps>lockout command has the highest priority, a failed working line using the
protection line is switched back to itself even if it is in a fault condition. No switches to the
protection line are allowed when locked out.
7750 SR Interface Configuration Guide
Interface Configuration
Page 87