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Cisco ASA 5500 Series Configuration Guide using ASDM
Chapter27 Configuring OSPF
Customizing OSPF
•The Transmit Delay, which specifies the estimated time, in seconds, required to send an LSA packet
on the interface. LSAs in the update packet have their ages increased by the amount specified by this
field before transmission. If the delay is not added before transmission over a link, the time in which
the LSA propagates over the link is not considered. The value assigned should take into account the
transmission and propagation delays for the interface. This setting has more significance on very
low-speed links. Valid values range from 1 to 65535 seconds. The default value is 1 second.
•The Dead Interval, which specifies the interval, in seconds, in which no hello packets are received,
causing neighbors to declare a router down. Valid values range from 1 to 65535. The default value
of this setting is four times the interval that was set in the Hello Interval field.
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:
Step1 In the main ASDM window, choose Configuration > Device Setup > Routing > OSPF > Setup.
Step2 Click the Area/Networks tab.
The Add OSPF Area dialog box appears.
Step3 Choose one of the following Area Type options:
•Normal to make the area a standard OSPF area. This option is selected by default when you first
create an area.
•Stub to make 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 (Types 3 and 4) from being flooded into
the area by unchecking the Summary check box.
•Summary to prevent LSAs from being sent into the stub area when the area being defined is a stub
area, uncheck this check box. By default, this check box is checked for stub areas.
•NSSA to make the area a not-so-stubby area. NSSAs accept Type 7 LSAs. When you create the
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 checking the Default Information Originate check box.
Step4 Enter the IP address in the IP Address field of the network or host to be added to the area. Use 0.0.0.0
with a netmask of 0.0.0.0 to create the default area. You can only enter 0.0.0.0 in one area.
Step5 Enter the network mask in the Network Mask field for the IP address or host to be added to the area. If
adding a host, choose the 255.255.255.255 mask.
Step6 Choose the OSPF Authentication type from the following options:
•None to disable OSPF area authentication. This is the default setting.