To implement OSPF functions, configure NBMA network attributes.
The NBMA network must be fully meshed. Any two routers on the NBMA network must be directly reachable. In most cases, however, this requirement cannot be met. To resolve this problem, run specific commands to forcibly change the network type to NBMA. For details, see Configuring Network Types for OSPF Interfaces.
The interval at which Hello packets for polling are sent by an NBMA interface is set.
On the NBMA network, after the neighbor relationship becomes invalid, the router sends Hello packets at an interval defined in the polling mechanism.
Sets the priority of an interface that runs for the DR or BDR.
The priority of an interface determines whether the interface is qualified to be a DR or BDR. The interface with the highest priority is elected as the DR or BDR. If the priority of an interface on a device is 0, the device cannot be elected as a DR or BDR. On a broadcast or an NBMA network, you can set the priority of an interface to control the DR or BDR selection. When the DR and BDR are elected on a network segment, they send DD packets to all neighboring nodes and set up adjacencies with all neighboring nodes.
If no Backup Seen event is received within the interval, the designated router (DR) election starts. Setting a proper value for the wait timer can slow down changes of the DR and the backup designated router (BDR) on the network, reducing network flapping. When setting the wait timer, note the following points:
The interface with the network type of NBMA cannot broadcast Hello packets to discover neighboring routers. Therefore, the IP address of a neighboring router must be configured on the process and whether the neighboring router can participate in DR election must be determined on the process.
The configuration is committed.