Brocade TurboIron 24X Series Configuration Guide - Manual (Page 673)

Brocade TurboIron 24X Series Configuration Guide 639
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Configuring OSPF
Configure default route origination
When the Layer 3 Switch is an OSPF Autonomous System Boundary Router (ASBR), you can
configure it to automatically generate a default external route into an OSPF routing domain. This
feature is called “default route origination” or “default information origination”.
By default, Layer 3 Switches do not advertise the default route into the OSPF domain. If you want
the Layer 3 Switch to advertise the OSPF default route, you must explicitly enable default route
origination.
When you enable OSPF default route origination, the Layer 3 Switch advertises a type 5 default
route that is flooded throughout the AS (except stub areas and NSSAs). In addition, internal NSSA
ASBRs advertise their default routes as translatable type 7 default routes.
The Layer 3 Switch advertises the default route into OSPF even if OSPF route redistribution is not
enabled, and even if the default route is learned through an IBGP neighbor.
NOTE
Layer 3 Switches never advertise the OSPF default route, regardless of other configuration
parameters, unless you explicitly enable default route origination using the following method.
If the Layer 3 Switch is an ASBR, you can use the “always” option when you enable the default route
origination. The always option causes the ASBR to create and advertise a default route if it does
not already have one configured.
If default route origination is enabled and you disable it, the default route originated by the Layer 3
Switch is flushed. Default routes generated by other OSPF routers are not affected. If you
re-enable the feature, the feature takes effect immediately and thus does not require you to reload
the software.
NOTE
The ABR (Layer 3 Switch) will not inject the default route into an NSSA by default and the command
described in this section will not cause the Layer 3 Switch to inject the default route into the NSSA.
To inject the default route into an NSSA, use the area <num> | <ip-addr> nssa
default-information-originate command. Refer to
“Assign a Not-So-Stubby Area (NSSA)” on
page 618.
To enable default route origination, enter the following command.
TurboIron(config-ospf-router)#default-information-originate
To disable the feature, enter the following command.
TurboIron(config-ospf-router)#no default-information-originate
Syntax: [no] default-information-originate [always] [metric <value>] [metric-type <type>]
The always parameter advertises the default route regardless of whether the router has a default
route. This option is disabled by default.
The metric <value> parameter specifies a metric for the default route. If this option is not used, the
default metric is used for the route.
The metric-type <type> parameter specifies the external link type associated with the default route
advertised into the OSPF routing domain. The <type> can be one of the following:
• 1 – Type 1 external route
• 2 – Type 2 external route