Brocade Communications Systems ICX 7250 series, Руководство по настройке

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Default route origination
When the device is an OSPFv2 Autonomous System Boundary Router (ASBR), you can configure it to automatically generate a default
external route into an OSPFv2 routing domain.
By default, a device does not advertise the default route into the OSPFv2 domain. If you want the device to advertise the OSPFv2
default route, you must explicitly enable default route origination. When you enable OSPFv2 default route origination, the device
advertises a type 5 default route that is flooded throughout the autonomous system, with the exception of stub areas.
The device advertises the default route into OSPFv2 even if OSPFv2 route redistribution is not enabled, and even if the default route is
learned through an IBGP neighbor. The device does not, however, originate the default route if the active default route is learned from an
OSPFv2 device in the same domain.
NOTE
The device does not advertise the OSPFv2 default route, regardless of other configuration parameters, unless you explicitly
enable default route origination.
If default route origination is enabled and you disable it, the default route originated by the device is flushed. Default routes generated by
other OSPFv2 devices are not affected. If you re-enable the default route origination, the change takes effect immediately and you do
not need to reload the software.
External route summarization
An ASBR can be configured to advertise one external route as an aggregate for all redistributed routes that are covered by a specified
address range.
When you configure an address range, the range takes effect immediately. All the imported routes are summarized according to the
configured address range. Imported routes that have already been advertised and that fall within the range are flushed out of the
autonomous system and a single route corresponding to the range is advertised.
If a route that falls within a configured address range is imported by the device, no action is taken if the device has already advertised the
aggregate route; otherwise, the device advertises the aggregate route. If an imported route that falls within a configured address range is
removed by the device, no action is taken if there are other imported routes that fall within the same address range; otherwise, the
aggregate route is flushed.
You can configure up to 32 address ranges. The device sets the forwarding address of the aggregate route to 0 and sets the tag to 0. If
you delete an address range, the advertised aggregate route is flushed and all imported routes that fall within the range are advertised
individually. If an external link-state database (LSDB) overflow condition occurs, all aggregate routes and other external routes are flushed
out of the autonomous system. When the device exits the external LSDB overflow condition, all the imported routes are summarized
according to the configured address ranges.
NOTE
If you use redistribution filters in addition to address ranges, the device applies the redistribution filters to routes first, and then
applies them to the address ranges.
NOTE
If you disable redistribution, all the aggregate routes are flushed, along with other imported
routes.
Default route origination
Brocade FastIron Layer 3 Routing Configuration Guide
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