Switch-Over Process For Transmitted Data; Switch-Over Process For Received Data; Aps Switch After Cpm Switchover - Alcatel-Lucent 7750 SR OS Interface Configuration Manual

Switch-Over Process for Transmitted Data

For packets arriving on all interfaces that need to be transmitted over APS protected interfaces, the
next hop associated with all these interfaces are programmed in all Flexible Fast-Path complexes
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 channel 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 channel on IOM-2 / MDA-1. When the transmitted data
needs to be switched from the working to the protect channel, only the relevant next hop indexes
need to be changed to the pre-programmed next-hop information for the protect channel on IOM-
2 / MDA-1.
Although the control CPM on the SF/CPM blade initiates the changeover between the working to
protect channel, 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 channel.

Switch-Over Process for Received Data

The Flexible Fast-Path complexes for both working and protect channels are programmed to
process ingress. The inactive (protect) channel however is programmed to ignore all packet data.
To perform the switch-over from working channel to the protect channel the Flexible Fast-Path
complex for the working channel is set to ignore all data while the Flexible Fast-Path complex of
the protect channel will be changed to accept data.

APS Switch After CPM Switchover

Immediately after a CPM switchover, there is a period during which the former standby CPM that
is transitioning to the active state needs to audit all the APS IOMs.
7750 SR OS Interface Configuration Guide
Interface Configuration
Page 59