ospf smart-discover

Usage Scenario

Generally, routers periodically send Hello packets on OSPF interfaces. By sending Hello packets, routers can establish and maintain neighbor relationship and elect the DR and the BDR on the multi-access network (broadcast or NBMA). The interface does not send Hello packets until the Hello timer expires when establishing neighboring relationships or electing the DR and the BDR on the multi-address network. Therefore, establishing neighboring relationships and the speed of electing the DR and the BDR.

After you enable smart-discover, the router can send Hello packets to the neighbor actively rather than wait for the expiration of the Hello timer when the neighbor status of a router or the DR or the BDR on the multi-address network of the broadcast or NBMA type changes.

Implementation Procedure

On broadcast or NBMA network, the neighboring relationships and the DR and the BDR are rapidly elected.

• When the neighbor status becomes 2-way for the first time or returns to Init from the 2-way or higher state, the interface enabled with smart-discover sends Hello packets to a neighbor without waiting for the timeout of the Hello timer when detecting that the neighbor status changes.
• When the interface status of the DR or the BDR on the multi-address network changes, the interface enabled with smart-discover sends Hello packets to the network segment and then participates in the DR or BDR election.

On a P2P or P2MP network, neighboring relationships are rapidly established the same way as on the broadcast or NBMA network.

Configuration Impact

The interval for sending Hello packets on the interface is determined by the interval for sending Hello packets configured on the interface.

Precautions

The default interval for sending Hello packets varies with the network type.