The ospf timer hello command sets the interval for sending Hello packets on an interface.
The undo ospf timer hello command restores the default value of the interval.
By default, for the interface of P2P and Broadcast type, the interval for sending Hello packets is 10 seconds; for the interface of P2MP and NBMA type, it is 30 seconds.
| Parameter | Description | Value |
|---|---|---|
| interval | Specifies the interval for sending the Hello packet on an interface. | The value is an integer ranging from 1 to 65535, in seconds. |
| conservative | Indicates the conservative mode of the dead timer. If the conservative mode is configured, the value configured for the dead timer using the ospf timer dead command takes effect even when the value is less than 20s. | - |
Ethernet interface view, Ethernet sub-interface view, Eth-Trunk interface view, Eth-Trunk sub-interface view, Tunnel interface view, Dialer interface view, VLANIF interface view, Virtual-Template interface view, BDIF interface view
Usage Scenario
Hello packets are periodically sent on OSPF interfaces to establish and maintain neighbor relationships. A Hello packet contains information about timers, DRs, BDRs, and known neighbors.
The smaller the value of hello interval is, the faster the network topology changes and the more network resources are consumed. Ensure that the parameters of this interface and the adjacent routers are consistent.
Precautions
OSPF cannot be configured on the Null interface.
If hello interval is set but a dead interval is not set using the ospf timer dead command, the dead interval of an OSPF neighbor is four times the value of hello interval. If the dead interval of an OSPF neighbor is shorter than 20s, the session may be closed. Therefore, if hello interval is shorter than 5s, the actual dead interval of an OSPF neighbor is not shorter than 20s.
To speed up OSPF convergence in the case of a link failure, for details, see Configuring BFD for OSPF.