Cisco Cisco IOS Software Release 12.4(6)T

cutover—An event in which system control and routing protocol execution are transferred from an 
active processor to a standby processor. This may include transfer of the packet forwarding function as 
well. 

NSF—Non-stop forwarding. The continuation of forwarding packets across line cards during RP 
cutover.

OSPF—Open Shortest Path First interior gateway routing protocol.

RF—Redundancy Facility.

RP—Route Processor.

switchover—See cutover.

See 

 for terms not included in this glossary.

 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For release information about a 
specific command, see the command reference documentation.

Cisco IOS software images are specific to a Cisco IOS software release, a feature set, and a platform. 
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image 
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 lists only the Cisco IOS software release that introduced support for a given feature in a given 

Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS 
software release train also support that feature.

OSPF RFC 3623 Graceful Restart Helper Mode

12.4(6)T

This document focuses on non-stop forwarding (NSF) for 
OSPFv2 in Cisco IOS software, using IETF standardized 
graceful restart functionality as described in RFC 3623.