Dell EMC SmartFabric OS10 User Guide Release 10.5.0

Graceful restart

OS10 offers graceful restart capability for BGP in helper mode only.

A BGP router whose neighbor is restarting is called a "helper."

If graceful restart is enabled on the restarting router, during restart, the helper maintains the routes that it has learned from its neighbor.

After the switch over, the graceful restart operation begins. Both routers reestablish their neighbor relationship and exchange their BGP routes again. The helper continues to forward prefixes pointing to the restarting peer, and the restarting router continues to forward traffic to its peers even though those neighbor relationships are restarting. When the restarting router receives all route updates from all BGP peers that are graceful restart capable, the graceful restart is complete. BGP sessions become operational again.