для Cisco Cisco IOS Software Release 12.0(29)S

Configure RSVP on routers.

Enable MPLS.

Configure TE on routers.

Enable graceful restart.

Graceful restart supports node failure only.

Graceful restart does not support restart or recovery on Cisco nodes, but helps in recovering a 
neighbor that is restart capable. Cisco routers advertise a restart time of 5 milliseconds and a 
recovery time of 0 in hello messages. 

Unnumbered interfaces are not supported.

To configure MPLS TE—RSVP Graceful Restart, you need to understand the following concepts:

Graceful restart allows RSVP TE enabled nodes to start gracefully following a node failure in the 
network such that the RSVP state after the failure is restored as quickly as possible. The node failure 
may be completely transparent to other nodes in the network as far as the RSVP state is concerned.

Graceful restart preserves the label values and forwarding information and works with third-party or 
Cisco routers seamlessly.

Graceful restart depends on RSVP hello messages that include Hello Request or Hello Acknowledgment 
(ACK) objects between two neighbors. 

As shown in 

, the graceful restart extension to these messages adds an object called Restart_Cap, 

which tells neighbors that a node may be capable of restarting if a failure occurs. The TTL in these 
messages is set to 255 so that adjacencies can be maintained through alternate paths even if the link 
between two neighbors goes down.