Alcatel-Lucent 7750 - Figure 14: APS Working and Protection Circuit Example

Port Features
Page 86 7750 SR Interface Configuration Guide
Note: In Annex B operation, all switch requests are for a switch from the primary section to the
secondary section. Once a switch request clears normally, traffic is maintained on the section to
which it was switched by making that section the primary section. The primary section may be
working circuit 1 or working circuit 2 at any particular moment.
Protection of Upper Layer Protocols and Services
APS prevents upper layer protocols and services from being affected by the failure of the active
circuit.
The following example with figures and description illustrate how services are protected during a
single-chassis APS switchover.
Figure 14: APS Working and Protection Circuit Example
Figure 14 is an example in which the APS working circuit is connected to IOM-1 / MDA-1 and the
protection circuit is connected to IOM-2 / MDA-1. In this example, assume that the working
circuit is currently used to transmit and receive data.
Switchover 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
IOM-CPU
MDA-1
Flexible FastPath
Complex
MDA-2
Flexible FastPath
Complex
IOM-CPU
APS-CTL
Services
IOM-CPU
APS Working
MDA-1
Flexible FastPath
Complex
MDA-2
Flexible FastPath
Complex
MDA-1
Flexible FastPath
Complex
MDA-2
Flexible FastPath
Complex
APS Protect
IOM-1
IOM-2
IOM-3
Fig_4