Configuring Ospf Area Parameters - Cisco Catalyst 3750 Software Configuration Manual

Configuring OSPF
Command
Step 13 show ip ospf interface [interface-name]
Step 14
copy running-config startup-config
Use the no form of these commands to remove the configured parameter value or return to the
default value.

Configuring OSPF Area Parameters

You can optionally configure several OSPF area parameters. These parameters include authentication for
password-based protection against unauthorized access to an area, stub areas, and not-so-stubby-areas
(NSSAs). Stub areas are areas into which information on external routes is not sent. Instead, the area
border router (ABR) generates a default external route into the stub area for destinations outside the
autonomous system (AS). An NSSA does not flood all LSAs from the core into the area, but can import
AS external routes within the area by redistribution.
Route summarization is the consolidation of advertised addresses into a single summary route to be
advertised by other areas. If network numbers are contiguous, you can use the area range router
configuration command to configure the ABR to advertise a summary route that covers all networks in
the range.
The OSPF area router configuration commands are all optional.
Note
Beginning in privileged EXEC mode, follow these steps to configure area parameters:
Command
Step 1
configure terminal
Step 2 router ospf process-id
Step 3
area area-id authentication
Step 4
area area-id authentication message-digest (Optional) Enable MD5 authentication on the area.
Step 5
area area-id stub [no-summary]
Step 6
area area-id nssa [no-redistribution]
[default-information-originate]
[no-summary]
Catalyst 3750 Metro Switch Software Configuration Guide
28-32
Purpose
Display OSPF-related interface information.
(Optional) Save your entries in the configuration file.
Purpose
Enter global configuration mode.
Enable OSPF routing, and enter router configuration mode.
(Optional) Allow password-based protection against unauthorized
access to the identified area. The identifier can be either a decimal
value or an IP address.
(Optional) Define an area as a stub area. The no-summary keyword
prevents an ABR from sending summary link advertisements into the
stub area.
(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.
Chapter 28 Configuring IP Unicast Routing
78-15870-01