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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter38 Configuring IP Unicast Routing
Configuring OSPF
Use the no form of these commands to remove the configured parameter value or to return to the
default value.
Configuring Other OSPF Parameters
You can optionally configure other OSPF parameters in router configuration mode.
•Route summarization: When redistributing routes from other protocols as described in the “Using
Route Maps to Redistribute Routing Information” section on page38-94, each route is advertised
individually in an external LSA. To help decrease the size of the OSPF link state database, you can
use the summary-address router configuration command to advertise a single router for all the
redistributed routes included in a specified network address and mask.
•Virtual links: In OSPF, all areas must be connected to a backbone area. You can establish a virtual
link in case of a backbone-continuity break by configuring two Area Border Routers as endpoints of
a virtual link. Configuration information includes the identity of the other virtual endpoint (the other
ABR) and the nonbackbone link that the two routers have in common (the transit area). Virtual links
cannot be configured through a stub area.
•Default route: When you specifically configure redistribution of routes into an OSPF routing
domain, the route automatically becomes an autonomous system boundary router (ASBR). You can
force the ASBR to generate a default route into the OSPF routing domain.
•Domain Name Server (DNS) names for use in all OSPF show privileged EXEC command displays
makes it easier to identify a router than displaying it by router ID or neighbor ID.
Step5 area area-id stub [no-summary] (Optional) Define an area as a stub area. The no-summary keyword
prevents an ABR from sending summary link advertisements into the
stub area.
Step6 area area-id nssa [no-redistribution]
[default-information-originate]
[no-summary]
(Optional) Defines an area as a not-so-stubby-area. Every router
within the same area must agree that the area is NSSA. Select one of
these keywords:
•no-redistribution—Select when the router is an NSSA ABR and
you want the redistribute command to import routes into normal
areas, but not into the NSSA.
•default-information-originate—Select on an ABR to allow
importing type 7 LSAs into the NSSA.
•no-redistribution—Select to not send summary LSAs into the
NSSA.
Step7 area area-id range address mask (Optional) Specify an address range for which a single route is
advertised. Use this command only with area border routers.
Step8 end Return to privileged EXEC mode.
Step9 show ip ospf [process-id]
show ip ospf [process-id [area-id]] database
Display information about the OSPF routing process in general or for
a specific process ID to verify configuration.
Display lists of information related to the OSPF database for a
specific router.
Step10 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose