KB.15.15

Example

Example 93 SPF throttling configuration

The last SPF calculation was scheduled and triggered at the 100th second. A new topology event

occurred at the 104th second. The configured values are:

• start-interval = 3 seconds

• wait-interval = 3 seconds

• max-wait-time = 500 seconds

HP Switch(ospf)# spf-throttle start-interval 3 wait-interval 3 max-wait-time 500

• The difference between the last SPF (100), added to the current SFP throttle interval (3), is less

than the time of the occurrence of the network event (104.) SPF is scheduled to run instantly

and the current SPF throttle interval is configured to 3 seconds (the start-interval value.)

• Another topology event occurs within the above 3 second SPF throttle interval, at the 106th

second. SPF is scheduled to run again at the 107th second (last event at 104th second+

wait-interval of 3 seconds), which is greater than the current event (106th second.) The SPF

timer is scheduled to run after 1 second. After that, the current SPF throttle interval is changed

to 10 seconds, the current wait-interval value.

• If another topology event occurs at the 110th second, which is within the 10 second current

wait-time. SPF is scheduled to run again at the 117th second (last SPF of 107 seconds +

wait-interval of 10 seconds), which is greater than the current event (110 seconds.) The SPF

timer is scheduled to run after 7 seconds. The current SPF wait-time is doubled to 20 seconds.

If any topology event occurs during the dynamic wait-interval, SPF is scheduled according to the

formula:

Last SPF + current dynamic wait-interval - time of occurrence of the event

The dynamic wait-interval keeps doubling until the max-wait-time is reached. If the

max-wait-time is reached and the network continues to be unstable, the dynamic wait-time

is set to the max-wait-time until the network stabilizes.

If the network stabilizes during a dynamic wait-interval period, SPF is calculated immediately

and the current SPF wait-interval is set to the configured start-interval.

Viewing OSPF information

Viewing general OSPF configuration information

Syntax:

show ip ospf general

166 Open Shortest Path First Protocol (OSPF)