Configure External Route Summarization - Brocade Communications Systems FastIron SX 800 Configuration Manual

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
Router OSPF: Enabled
Nonstop Routing: Disabled
Graceful Restart: Disabled
Graceful Restart Helper: Enabled
Graceful Restart Time: 120
Graceful Restart Notify Time: 0
Redistribution: Disabled
FastIron Ethernet Switch Layer 3 Routing
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Configuring OSPF
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