The ospf timer hello command sets an interval for sending Hello packets on an interface.
The undo ospf timer hello command restores the default value of the interval.
By default, for a P2P or broadcast interface, the interval for sending Hello packets is 10 seconds; for an NBMA or P2MP interface, it is 30 seconds.
| Parameter | Description | Value |
|---|---|---|
| interval | Specifies an interval for sending the Hello packet on an interface. | The value is an integer ranging from 1 to 65535, in
seconds. Setting interval to be longer than or equal to 5s is recommended. |
| 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. | - |
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 hello interval is, the faster the changing speed of the network topology is. The cost of routes, however, becomes greater. Ensure that the parameters of this interface and the adjacent routers are consistent.
Precautions
OSPF does not support the configuration on a 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.
# Set the interval for sending Hello packets on VLANIF100 to 20 seconds.
<HUAWEI> system-view
[HUAWEI] interface vlanif 100
[HUAWEI-Vlanif100] ospf timer hello 20
# Set the interval for sending Hello packets on GE0/0/1 to 20 seconds.
<HUAWEI> system-view [HUAWEI] interface gigabitethernet 0/0/1 [HUAWEI-GigabitEthernet0/0/1] undo portswitch [HUAWEI-GigabitEthernet0/0/1] ospf timer hello 20