Cisco Systems Configuring Route Summarization When Redistributing Routes Into OSPF

27-6
Cisco ASA 5500 Series Configuration Guide using ASDM
Chapter27 Configuring OSPF
Customizing OSPF
When redistributing from one OSPF process to another OSPF process on the same device, the metric will
be carried through from one process to the other if no metric value is specified. When redistributing other
processes to an OSPF process, the default metric is 20 when no metric value is specified.
Step7 Choose one of the following options for the Metric Type.
•If the metric is a Type 1 external route, choose 1.
•If the metric is a Type 2 external route, choose 2.
Step8 Enter the tag value in the Tag Value field.
The tag value is a 32-bit decimal value attached to each external route that is not used by OSPF itself,
but may be used to communicate information between ASBRs. Valid values range from 0 to
4294967295.
Step9 Check the Use Subnets check box to enable the redistribution of subnetted routes. Uncheck this check
box to cause only routes that are not subnetted to be redistributed.
Step10 Choose the name of the route map to apply to the redistribution entry from the Route Map drop-down
list.
Step11 If you need to add or configure a route map, click Manage.
The Configure Route Map dialog box appears.
Step12 Click Add or Edit to define which of the routes from the specified routing protocol are allowed to be
redistributed into the target routing process. For more information, see the “Defining a Route Map”
section on page 26-4.
Step13 Click OK.
Configuring Route Summarization When Redistributing Routes Into OSPF
When routes from other protocols are redistributed into OSPF, each route is advertised individually in
an external LSA. However, you can configure the ASA to advertise a single route for all the redistributed
routes that are included for a specified network address and mask. This configuration decreases the size
of the OSPF link-state database.
Routes that match the specified IP Address mask pair can be suppressed. The tag value can be used as a
match value for controlling redistribution through route maps.
There are two areas that you can configure for route summarization:
•Adding a Route Summary Address, page27-6
•Adding or Editing an OSPF Summary Address, page27-7
Adding a Route Summary Address
The Summary Address pane displays information about the summary addresses configured for each
OSPF routing process.
Routes learned from other routing protocols can be summarized. The metric used to advertise the
summary is the smallest metric of all the more specific routes. Summary routes help reduce the size of
the routing table.