ospf smart-discover

Usage Scenario

In normal situations, devices periodically send Hello packets through OSPF interfaces. By sending Hello packets, devices set up and maintain neighbor relationships, and elect the DR and BDR on the multi-access network (broadcast or NBMA network). When setting up neighbor relationships or electing the DR and BDR on the multi-access network, interfaces send Hello packets only when the Hello timer expires. This slows down the establishment of neighbor relationships and election of the DR and BDR.

After smart-discover is configured, when the status of the neighbor relationship changes or the DR and BDR on the multi-access network changes, the device sends Hello packets to its neighbor immediately without waiting for the expiration of the Hello timer.

Procedure

On broadcast and NBMA networks, neighbor relationships can be rapidly set up and a DR and a BDR can be 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 smart-discover-enabled interface sends Hello packets to a neighbor without waiting for the expiration of the Hello timer when detecting that the neighbor status changes.
• When the status of the interface functioning as the DR or BDR on the multi-access network changes, the smart-discover-enabled interface actively sends Hello packets on the network segment and then participates in the DR or BDR election.

The principle of setting up adjacencies rapidly on P2P or P2MP networks is the same as that on broadcast and NBMA networks.

Configuration Impact

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

Precautions

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