Cisco Cisco IOS Software Release 12.0(22)S

This document describes the Frame Relay Fast Restart feature in Cisco IOS Release 12.0(22)S. It 
includes the following sections:

The Frame Relay Fast Restart feature increases network availability by reducing recovery time from 
Route Processor (RP) failures on Cisco 7500 series and Cisco 10000 series routers in Frame Relay 
networks. This feature reduces recovery time by accelerating the transition from primary RP to standby 
RP after a hardware or software failure.

When a switchover from primary RP to standby RP occurs on a switch with Frame Relay line cards, the 
switch must implement an initialization procedure to bring permanent virtual circuits (PVCs) back up 
and to reestablish dynamic mappings. While this procedure is under way, the Frame Relay interface is 
unavailable for traffic forwarding. Before the introduction of this feature, the initialization procedure 
took from 30 to 90 seconds to complete on each Frame Relay interface. The Frame Relay Fast Restart 
feature reduces interface restart time to 10 to 15 seconds. 

The Frame Relay Fast Restart feature uses the methods described in the following sections to reduce 
interface restart time:

12.0(18)ST

This feature was introduced on the Cisco 10000 series routers.

12.0(19)ST1

This feature was introduced on the Cisco 7500 series routers.

12.0(22)S

This feature was integrated into Cisco IOS Release 12.0(22)S.