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Cisco ASA 5500 Series Configuration Guide using ASDM
OL-20339-01
Chapter 21 Configuring OSPF
Customizing OSPF
Configuring OSPF Area Parameters
You can configure several OSPF area parameters. These area parameters (shown in the following task
list) include setting authentication, defining stub areas, and assigning specific costs to the default
summary route. Authentication provides password-based protection against unauthorized access to an
area.
Stub areas are areas into which information on external routes is not sent. Instead, there is a default
external route generated by the ABR, into the stub area for destinations outside the autonomous system.
To take advantage of the OSPF stub area support, default routing must be used in the stub area.
To specify area parameters for your network, perform the following steps:
Step 1 In the main ASDM window, choose Configuration > Device Setup > Routing > OSPF > Setup.
Step 2 Click the Area/Networks tab.
The Add OSPF Area dialog box appears.
Step 3 Select one of the Area Type options.
Options include:
• Normal—Choose this option to make the area a standard OSPF area. This option is selected by
default when you first create an area.
• Stub—Choosing this option makes the area a stub area. Stub areas do not have any routers or areas
beyond it. Stub areas prevent AS External LSAs (Type 5 LSAs) from being flooded into the stub
area. When you create a stub area, you have the option of preventing summary LSAs (Type 3 and 4)
from being flooded into the area by unchecking the Summary check box.
• Summary—When the area being defined is a stub area, unchecking this check box prevents LSAs
from being sent into the stub area. This check box is selected by default for stub areas.
• NSSA—Choose this option to make the area a not-so-stubby area. NSSAs accept Type 7 LSAs.
When you create a NSSA, you have the option of preventing summary LSAs from being flooded
into the area by unchecking the Summary check box. You can also disable route redistribution by
unchecking the Redistribute check box and enabling Default Information Originate.
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