Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 276)

Configure external route summarization
When the device is an OSPF Autonomous System Boundary Router (ASBR), you can configure it 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 AS 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 with in a configured address range is removed by the device, no
action is taken if there are other imported routes that fall with in 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 zero and sets the tag to zero.
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 LSDB overflow condition occurs, all aggregate routes are flushed out of the AS, along
with other external routes. 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, then applies them to the address ranges.
NOTE
If you disable redistribution, all the aggregate routes are flushed, along with other imported routes.
NOTE
This option affects only imported, type 5 external routes. A single type 5 LSA is generated and flooded
throughout the AS for multiple external routes. Type 7-route redistribution is not affected by this
feature. All type 7 routes will be imported (if redistribution is enabled). To summarize type 7 LSAs or
exported routes, use NSSA address range summarization.
To configure a summary address for OSPF routes, enter commands such as the following.
device(config-ospf-router)# summary-address 10.1.0.0 255.255.0.0
The command in this example configures summary address 10.1.0.0, which includes addresses
10.1.1.0, 10.1.2.0, 10.1.3.0, and so on. For all of these networks, only the address 10.1.0.0 is
advertised in external LSAs.
Syntax: summary-address ip-addr ip-mask
The ip-addr parameter specifies the network address.
The ip-mask parameter specifies the network mask.
To display the configured summary addresses, enter the following command at any level of the CLI.
device# show ip ospf config
Configure external route summarization
276 FastIron Ethernet Switch Layer 3 Routing Configuration Guide
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