10G Core Routing Switch User Manual
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Setting a Shortest Path First (SPF) Calculation Interval for OSPF
Whenever the LSDB of OSPF takes changes, the shortest path requires recalculation. Calculating the shortest path
upon change will consume enormous resources as well as affect the operation efficiency of the router. Adjusting the
SPF calculation interval, however, can restrain the resource consumption due to frequent network changes.
Beginning in OSPF configuration mode, follow these steps to set a Shortest Path First (SPF) Calculation Interval for
OSPF.
Command
Purpose
Step 1
timers spf
delay-seconds
hold-seconds
Set the SPF calculation interval
By default, the interval of SPF recalculation is 5
seconds.
Step 2
exit
Return to global configuration mode.
Step 3
exit
Return to privileged EXEC mode.
Step 4
show ip ospf
Verify your entries.
Step 5
Copy
running-config
startup-config
(Optional) Save your entries in the configuration file.
To restore the SPF calculation interval, use
no timers spf
OSPF configuration command.
Configuring STUB Area of OSPF
STUB areas are some special LSA areas, in which the ABRs do not propagate the learned external routes of the AS. In
these areas, the routing table sizes of routers and the routing traffic are significantly reduced.
The STUB area is an optional configuration attribute, but not every area conforms to the configuration condition.
Generally, STUB areas, located at the AS boundaries, are those non-backbone areas with only one ABR. Even if this
area has multiple ABRs, no virtual links are established between these ABRs.
To ensure that the routes to the destinations outside the AS are still reachable, the ABR in this area will generate a
default route (0.0.0.0) and advertise it to the non-ABR routers in the area.
Please pay attention to the following items when configuring a STUB area:
The backbone area cannot be configured to be the STUB area and the virtual link cannot pass through the STUB
area.
If you want to configure an area to be the STUB area, then all the routers in this area should be configured with
this attribute.
No ASBR can exist in a STUB area. In other words, the external routes of the AS cannot be propagated in the STUB
area.
Beginning in OSPF configuration mode, follow these steps to configure STUB Area of OSPF.
Command
Purpose
Step 1
area
area-id
stub
[CR|no-summary]
Configure an area to be the STUB area