OSPF Smart-Discover

Definition

Routers periodically send Hello packets through OSPF interfaces at the Hello interval specified in the Hello timer. This fixed interval slows down the establishment of OSPF neighbor relationships.

Enabling smart-discover can speed up establishment of OSPF neighbor relationships in certain scenarios.

**Table 1** OSPF smart-discover
Scenario	Processing
Smart-discover is not configured.	Hello packets are sent only when the Hello timer expires. Devices wait to receive Hello packets within the Hello interval to establish neighbor relationships.
Smart-discover is configured.	Hello packets are sent directly regardless of whether the Hello timer has expired. Devices receive packets without delay and can immediately transmit their status to establish neighbor relationships.

Principle

In the following scenarios, an interface with smart-discover enabled can send Hello packets to target devices without waiting for the expiration of the Hello timer:

The neighbor status becomes 2-way for the first time.
The neighbor status changes from 2-way or a higher state to Init.