Brocade BigIron RX Series Configuration Guide - Manual (Page 862)

784 BigIron RX Series Configuration Guide
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Configuring OSPF
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If default route origination is enabled and you disable it, the default route originated by the BigIron
RX 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 (BigIron RX) will not inject the default route into an NSSA by default and the command
described in this section will not cause the BigIron RX 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 763.
To enable default route origination, enter the following command.
BigIron RX(config-ospf-router)# default-information-originate
To disable the feature, enter the following command.
BigIron RX(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
If you do not use this option, the default redistribution metric type is used for the route type.
NOTE
If you specify a metric and metric type, the values you specify are used even if you do not use the
always option.
Configuring a default network route
The BigIron RX enables you to specify a candidate default route without the need to specify the next
hop gateway. If the IP route table does not contain an explicit default route (for example, 0.0.0.0/0)
or propagate an explicit default route through routing protocols, the software can use the default
network route as a default route instead.
When the software uses the default network route, it also uses the default network route's next hop
gateway as the gateway of last resort.
This feature is especially useful in environments where network topology changes can make the
next hop gateway unreachable. This feature allows the BigIron RX to perform default routing even if
the default network route's default gateway changes.
The feature thus differs from standard default routes. When you configure a standard default
route, you also specify the next hop gateway. If a topology change makes the gateway unreachable,
the default route becomes unusable.