H3C Technologies H3C S12500 Series Switches - Manual (Page 37)

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Step Command Remarks
2. Enter SPBM view. spbm N/A
3. Configure LSP fast-flooding.
flash-flood [ flood-count
flooding-count |
max-timer-interval
flooding-interval ] *
By default, LSP fast-flooding is
disabled.
Tuning the SPF calculation timer
The SPF calculation timer sets the delay between consecutive SPF calculations. You can decrease the
timer for ISIS-SPB to react quickly to topology changes, and decrease the timer to protect the CPU from
frequent SPF calculations.
The SPF timer is an exponential generation timer. With this timer, ISIS-SPB quickly responds to the first
events that trigger SPF calculation, and then slows down to protect the CPU from frequent SPF
calculations.
The SPF calculation timer value is derived from three parameters: minimum wait time (minimum-interval),
base number for incremental wait time (incremental-interval), and maximum wait time
(maximum-interval).
When the network is stable, the SPF calculation timer is set to the minimum wait time for each SPF
computation. When the network is unstable, the SPF calculation timer increments by
incremental-interval×2
n-2 (n is the number of calculations) for each SPF calculation until the maximum wait
time is reached. If an event triggers SPF calculation after the maximum wait time is reached, the SPF
calculation timer re-initiates with the minimum wait time.
NOTE:
The network is considered unstable if the interval between consecutive SPF calculations is smaller than two
times the maximum wait time.
To tune the SPF calculation timer:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter SPBM view. spbm N/A
3. Set the SPF calculation
exponential backoff
timers.
timer spf maximum-interval
[ minimum-interval
[ incremental-interval ] ]
Default values for the SPF calculation
timer parameters:
• maximum-interval—5 seconds.
• minimum-interval—10 milliseconds.
• incremental-interval—10
milliseconds.
The minimum interval and the
incremental interval must be shorter than
the maximum interval.