3Com Switch 8800 Configuration Guide
Chapter 19 OSPF Configuration
19-11
III. Configuring the default interval and number for OSPF to import external
routes
OSPF can import the external routing information and broadcast it to the entire
autonomous system. Importing routes too often and importing too many external routes
at one time will greatly affect the performance of the device. Therefore it is necessary to
specify the default interval and number for the protocol to import external routes.
Perform the following configuration in OSPF view.
Table 19-7
Configure the default interval and number for OSPF to import external
routes
Operation
Command
Configure the default interval for OSPF to
import external routes
default interval
seconds
Restore the default interval for OSPF to import
external routes
undo default interval
Configure the upper limit to the routes that
OSPF imports at a time
default limit
routes
Restore the default upper limit to the external
routes that can be imported at a time
undo default limit
By default, the interval for importing external routes is 1 second. The upper limit to the
external routes imported is 1000 at a time.
19.2.6 Configuring OSPF to Import Default Routes
By default, there are no default routes in a common OSPF area (either a backbone
area or a non-backbone area). Besides, the
import-route
command cannot be used to
import the default route.
Use the
default-route-advertise
command to generate and advertise a default route in
an OSPF route area. Note the following when you use this command:
z
If you use the
default-route-advertise
command on an ASBR or ABR of a
common OSPF area, the system generates a Type-5 LSA, advertising the default
route in the OSPF route area.
z
If you use the
default-route-advertise
command on an ASBR or ABR of an NSSA,
the system generates a Type-7 LSA, advertising the default route in the NSSA.
z
This command is invalid for a stub area or a totally stub area.
z
For an ASBR, the system generates the corresponding Type-5 LSA or Type-7
LSA by default when a default route existed in the routing table.
z
For an ABR, the system will generate a Type-5 LSA or Type-7 LSA no matter
whether there is a default route in the routing table.
