Dell PowerConnect B-RX Configuration Manual page 754

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Configuring OSPF
The ABR translates the Type-7 LSAs into Type-5 LSAs. If an area range is configured for the NSSA,
the ABR also summarizes the LSAs into an aggregate LSA before flooding the Type-5 LSAs into the
backbone.
Since the NSSA is partially "stubby" the ABR does not flood external LSAs from the backbone into
the NSSA. To provide access to the rest of the Autonomous System (AS), the ABR generates a
default Type-7 LSA into the NSSA.
Configuring an NSSA
To configure OSPF area 1.1.1.1 as an NSSA, enter the following commands.
BigIron RX(config)# router ospf
BigIron RX(config-ospf-router)# area 1.1.1.1 nssa 1
BigIron RX(config-ospf-router)# write memory
Syntax: area <num> | <ip-addr> nssa <cost> | default-information-originate
The <num> | <ip-addr> parameter specifies the area number, which can be a number or an IP
address format. If you specify an number, the number can be from 0 – 2,147,483,647.
The nssa <cost> | default-information-originate parameter specifies that this is a
Not-So-Stubby-Area (NSSA). The <cost> specifies an additional cost for using a route to or from this
NSSA and can be from 1 – 16777215. There is no default. Normal areas do not use the cost
parameter. Alternatively, you can use the default-information-originate parameter to cause the
device to inject the default route into the NSSA.
NOTE
The BigIron RX does not inject the default route into an NSSA by default.
To configure additional parameters for OSPF interfaces in the NSSA, use the ip ospf area...
command at the interface level of the CLI.
Configuring an address range for the NSSA
If you want the ABR that connects the NSSA to other areas to summarize the routes in the NSSA
before translating them into Type-5 LSAs and flooding them into the other areas, configure an
address range. The ABR creates an aggregate value based on the address range. The aggregate
value becomes the address that the ABR advertises instead of advertising the individual addresses
represented by the aggregate. You can configure up to 32 ranges in an OSPF area.
To configure an address range in NSSA 1.1.1.1, enter the following commands. This example
assumes that you have already configured NSSA 1.1.1.1.
BigIron RX(config)# router ospf
BigIron RX(config-ospf-router)# area 1.1.1.1 range 209.157.22.1 255.255.0.0
BigIron RX(config-ospf-router)# write memory
Syntax: [no] area <num> | <ip-addr> range <ip-addr> <ip-mask> [advertise | not-advertise]
The <num> | <ip-addr> parameter specifies the area number, which can be in IP address format. If
you specify a number, the number can be from 0 – 2,147,483,647.
The range <ip-addr> parameter specifies the IP address portion of the range. The software
compares the address with the significant bits in the mask. All network addresses that match this
comparison are summarized in a single route advertised by the router.
The <ip-mask> parameter specifies the portions of the IP address that a route must contain to be
summarized in the summary route. In the example above, all networks that begin with 209.157 are
summarized into a single route.
682 BigIron RX Series Configuration Guide
53-1001986-01