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Configuring OSPF Configuring OSPF
OmniSwitch 6800/6850/9000 Advanced Routing Configuration Guide December 2007 page 1-19
Configuring Stub Area Default Metrics
The default metric configures the type of cost metric that a default area border router (ABR) will adver-
tise in the default summary Link State Advertisement (LSA). Use the ip ospf area default-metric
command to create or delete a default metric for stub or Not So Stubby Area (NSSA) area. Specify the
stub area and select a cost value or a route type, as shown:
-> ip ospf area 1.1.1.1 default-metric 0 cost 50
or
-> ip ospf area 1.1.1.1 default-metric 0 type type1
A route has a preset metric associated to it depending on its type. The first example, the stub area is given
a default metric of 0 (this is Type of Service 0) and a cost of 50 added to routes from the area. The second
example specifies that the cost associated with Type 1 routes should be applied to routes from the area.
Note. At this time, only the default metric of ToS 0 is supported.
To remove the area default-metric setting, enter the ip ospf area default-metric command using the no
command, as shown:
-> no ip ospf area 1.1.1.1 default-metric 0
Setting Area Ranges
Area ranges are used to summarize many area routes into a single advertisement at an area boundary.
Ranges are advertised as summaries or NSSAs. Ranges also act as filters that either allow the summary to
be advertised or not. Ranges are created using the ip ospf area range command. An area and the summary
IP address and IP mask must be specified. For example, to create a summary range with IP address
192.5.40.1 and an IP mask of 255.255.255.0 for area 1.1.1.1, the following commands would be entered at
the CLI prompt:
-> ip ospf area 1.1.1.1 range summary 192.5.40.1 255.255.255.0
-> ip ospf area 1.1.1.1 range summary 192.5.40.1 255.255.255.0 effect noMatching
To view the configured ranges for an area, use the show ip ospf area range command as demonstrated:
-> show ip ospf area 1.1.1.1 range
Configuring a Totally Stubby Area
In order to configure a totally stubby area you need to configure the area as stub on the ABR and disable
summarization. By doing so the ABR will generate a default route in the totally stubby area. In addition,
the other routers within the totally stubby area must only have their area configured as stub.
For example, to configure the simple totally stubby configuration shown in the figure in “Configuring a
Totally Stubby Area” on page 1-19 where Router B is an ABR between the backbone area 0 and the stub
area 1 and Router A is in Totally Stubby Area 1.1.1.1 follow the steps below:
1 Enter the following commands on Router B:
-> ip load ospf
-> ip ospf area 0.0.0.0
-> ip ospf area 1.1.1.1
-> ip ospf area 1.1.1.1 type stub