302 CHAPTER 28: OSPF CONFIGURATION
n
■ The hello and dead intervals restore to default values after you change the
network type for an interface.
■ The dead interval should 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 should not be so small for avoidance of unnecessary
LSA retransmissions. In general, this value is bigger than the round-trip time of
a packet between two adjacencies.
Specifying an LSA
Transmission Delay
Since OSPF packets need time for traveling on links, extending LSA age time with a
delay is necessary, especially for low speed links.
Follow these steps to specify an LSA transmission delay on an interface:
Specifying SPF
Calculation Interval
The LSDB changes lead to SPF calculations. When an OSPF network changes
frequently, a large amount of network resources will be occupied, reducing the
working efficiency of routers. You can adjust the SPF calculation interval for the
network to reduce negative influence.
Follow these steps to configure SPF calculation interval:
n
With this task configured, when network changes are not frequent, SPF
calculation applies at the minimum-interval. If network changes become frequent,
SPF calculation interval is incremented by incremental-interval¬²2
n-2
(n is the
number of calculation times) each time a calculation occurs, up to the
maximum-interval.
Specifying the LSA
Minimum Repeat Arrival
Interval
After receiving the same LSA as the previously received LSA within the LSA
minimum repeat arrival interval, an interface discards the LSA.
Follow these steps to configure the LSA minimum repeat arrival interval:
To do… Use the command… Remarks
Enter system view system-view -
Enter interface view interface interface-type interface-number -
Specify an LSA transmission
delay
ospf trans-delay seconds Optional
1 second by default
To do… Use the command… Remarks
Enter system view system-view -
Enter OSPF view ospf [ process-id | router-id
router-id ] *
-
Specify SPF calculation
interval(s)
spf-schedule-interval
maximum-interval
[ minimum-interval
[ incremental-interval ]]
Optional
By default, the interval is 5
seconds.
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