3Com Switch 4800G 24-Port Configuration Manual page 302

302 C 28: OSPF C
HAPTER
n
Specifying an LSA
Transmission Delay
Specifying SPF
Calculation Interval
n
Specifying the LSA
Minimum Repeat Arrival
Interval
ONFIGURATION
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.
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:
To do...
Enter system view
Enter interface view
Specify an LSA transmission
delay
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:
To do...
Enter system view
Enter OSPF view
Specify SPF calculation
interval(s)
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
number of calculation times) each time a calculation occurs, up to the
maximum-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:
Use the command...
system-view
interface interface-type interface-number -
ospf trans-delay seconds
Use the command...
system-view
ospf [ process-id | router-id
router-id ] *
spf-schedule-interval
maximum-interval
[ minimum-interval
[ incremental-interval ] ]
Remarks
-
Optional
1 second by default
Remarks
-
-
Optional
By default, the interval is 5
seconds.
n-2 (n is the