spf-options (Protocols IS-IS)
Syntax
spf-options {
delay milliseconds;
holddown milliseconds;
rapid-runs number;
}
Hierarchy Level
[edit logical-systems logical-system-name protocols isis], [edit logical-systems logical-system-name routing-instances routing-instance-name protocols isis], [edit protocols isis], [edit routing-instances routing-instance-name protocols isis]
Description
Configure options for running the shortest-path-first (SPF) algorithm.
Running the SPF algorithm is usually the beginning of a series of larger system-wide events. For example, the SPF algorithm can lead to interior gateway protocol (IGP) prefix changes, which then lead to BGP nexthop resolution changes. Consider what happens if there are rapid link changes in the network. The local routing device can become overwhelmed. This is why it sometimes makes sense to throttle the scheduling of the SPF algorithm.
You can configure the following SPF options:
The delay in the time between the detection of a topology change and when the SPF algorithm actually runs.
The maximum number of times that the SPF algorithm can run in succession before the hold-down timer begins.
The time to hold down, or wait, before running another SPF calculation after the SPF algorithm has run in succession the configured maximum number of times.
If the network stabilizes during the hold-down period and the
SPF algorithm does not need to run again, the system reverts to the
configured values for the delay and rapid-runs statements.
Options
delay milliseconds—Time interval between the detection of a topology change
and when the SPF algorithm runs.
Range: 50 through 1000 milliseconds
Default: 200 milliseconds
holddown milliseconds—Time
interval to hold down, or wait before a subsequent SPF algorithm runs
after the SPF algorithm has run the configured maximum number of times
in succession.
Range: 2000 through 10,000 milliseconds
Default: 5000 milliseconds
rapid-runs number—Maximum
number of times the SPF algorithm can run in succession. After the
maximum is reached, the holddown interval begins.
Range: 1 through 5
Default: 3
Required Privilege Level
routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.
Release Information
Statement introduced in Junos OS Release 8.5.