87Configuration prerequisitesBefore configuring OSPF network optimization, complete the following tasks:• Configure IP addresses for interfaces• Configure OSPF basic functionsConfiguring OSPF packet timersYou can configure the following timers on OSPF interfaces as needed.• Hello timer—Interval for sending hello packets. It must be identical on OSPF neighbors. The longerthe interval, the lower the convergence speed, and the smaller the network load.• Poll timer—Interval for sending hello packets to a neighbor that is down on the NBMA network.• Dead timer—Interval within which if the interface receives no hello packet from the neighbor, itdeclares the neighbor is down.• LSA retransmission timer—Interval within which if the interface receives no acknowledgementpackets after sending an LSA to the neighbor, it retransmits the LSA.Follow these steps to configure timers for OSPF packets:To do… Use the command… RemarksEnter system view system-view —Enter interface view interface interface-typeinterface-number —Specify the hellointerval ospf timer hello secondsOptionalThe hello interval defaults to 10 seconds on P2Pand broadcast interfaces, and defaults to 30seconds on P2MP and NBMA interfaces.Specify the poll interval ospf timer poll seconds OptionalThe poll interval defaults to 120 seconds.Specify the deadinterval ospf timer dead secondsOptionalThe default dead interval is 40 seconds on P2Pand broadcast interfaces and 120 seconds onP2MP and NBMA interfaces.Specify theretransmission interval ospf timer retransmit intervalOptionalThe retransmission interval defaults to 5seconds.NOTE:• The hello and dead intervals restore to default values after you change the network type for an interface.• The dead interval must be at least four times the hello interval on an interface.• The poll interval is at least four times the hello interval.• The retransmission interval must not be so small to avoid unnecessary LSA retransmissions. In general,this value is bigger than the round-trip time of a packet between two neighbors.
