Adjusting SPF Calculation Time

When configuring, the spf-delay-ietf set of init-delay, short-delay, long-delay, holddown and time-to-learn should be submitted in the same commit.
When deleting, the command is delete protocols isis area-tag <text> [vrf <vrf-name>] spf-delay-ietf, and all the spf-delay-ietf configuration of init-delay, short-delay, long-delay, holddown and time-to-learn will be removed.

Adjusting SPF (Shortest Path First) calculation time in IS-IS allows for controlling the frequency of route computation when there are changes in the network's link-state database (LSDB). By modifying the SPF calculation time, network administrators can balance between route convergence speed and system resource utilization. If SPF calculation delay is too long, it may slow down route convergence, while if it's too short, it might consume excessive system resources. Adjusting this parameter is crucial for optimizing network performance.

SPF calculation time includes the following parameter configurations:

spf-interval: To configure the interval time for SPF calculation in IS-IS, you can use the set protocols isis area-tag <text> [vrf <vrf-name>] spf-interval <spf-interval> command. This command allows you to specify the time interval between consecutive SPF calculations. Adjusting this interval can impact route convergence speed and system resource utilization. Here's an example of how to configure it:

admin@PICOS# set protocols isis area-tag instance1 spf-interval 60
admin@PICOS# commit

init-delay: To configure the initial wait interval before SPF starts after receiving an updated LSA, you can use the set protocols isis area-tag <text> [vrf <vrf-name>] spf-delay-ietf init-delay <init-delay> command.
short-delay and long-delay: To configure the minimum and maximum time between two SPF runs, used to cap the spf holddown value. It also defines how long the network has to be stable before the wait interval is reset to the init-delay and holddown values, you can use the set protocols isis area-tag <text> [vrf <vrf-name>] spf-delay-ietf short-delay <short-delay> and set protocols isis area-tag <text> [vrf <vrf-name>] spf-delay-ietf long-delay <long-delay> commands.
holddown: To configure 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, you can use the set protocols isis area-tag <text> [vrf <vrf-name>] spf-delay-ietf holddown <holddown> command.
time-to-learn: To configure the maximum duration typically needed to learn all the IGP events related to a single component failure (such as router failure or SRLG failure), you can use the set protocols isis area-tag <text> [vrf <vrf-name>] spf-delay-ietf time-to-learn <time-to-learn> command.