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Routing & Switching · Foundational

OSPF Hello and Dead Intervals

OSPF timers: how often hellos are sent and how long to wait without hellos before declaring a neighbor down.

Definition

Defaults are 10/40 seconds on broadcast and point-to-point networks and 30/120 seconds on NBMA and point-to-multipoint. Both must match between neighbors. ip ospf dead-interval minimal hello-multiplier enables sub-second hellos, though BFD is now preferred.

Example

ip ospf hello-interval 5 ; ip ospf dead-interval 20

Exam tip

Changing the hello interval on Cisco automatically sets dead to four times hello unless dead is configured explicitly.

Related terms