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Routing & Switching · Advanced

Nonstop Routing (NSR)

A high-availability feature where the standby route processor maintains full routing protocol state so neighbors never notice a switchover.

Definition

Unlike graceful restart, NSR does not need helper support from neighbors because sessions (including BGP TCP state) are synchronized to the standby. Junos calls it nonstop active routing (NSR) and requires GRES.

Example

set routing-options nonstop-routing

Exam tip

NSR = no neighbor help needed; GR/NSF = neighbors must act as helpers.

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