Introduction To Graceful Restart; Basic Concepts In Graceful Restart - H3C S3610-28P Operation Manual

Operation Manual – BFD-GR
H3C S3610&S5510 Series Ethernet Switches
Go to these sections for information you are interested in:

Introduction to Graceful Restart

Basic Concepts in Graceful Restart

Graceful Restart Communication Procedure
Graceful Restart Mechanism for Several Commonly Used Protocols
Note:
Throughout this chapter, the term router in this document refers to a router in a generic
sense or a Layer 3 switch.
2.1 Introduction to Graceful Restart
Graceful Restart ensures the continuity of packet forwarding when a routing protocol
restarts.
The mechanism of Graceful Restart works as follows: after the routing protocol on a
Graceful Restart capable device restarts, the device will notify its neighbors to
temporarily preserve its adjacencies with them and the routing information. The
neighbors will help the restarting device to update its routing information and to restore
it to the state prior to the restart in minimal time. The routing and forwarding remain
highly stable across the restart, the packet forwarding path remains the same, and the
whole system can forward IP packets continuously. Hence, it is called "Graceful
Restart".
2.2 Basic Concepts in Graceful Restart
A router with the Graceful Restart feature enabled is called a Graceful Restart capable
router. It can perform a Graceful Restart when its routing protocol restarts. Routers that
are not Graceful Restart capable will follow the normal restart procedures after a
routing protocol restart.
GR Restarter: Graceful restarting router, the router whose routing protocol has
restarted due to administrator instructions or network failure. It must be Graceful
Restart capable.
GR Helper: The neighbor of the GR Restarter, which helps the GR Restarter to
retain the routing information. It must be Graceful Restart capable.
Chapter 2 GR
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Chapter 2 GR