Configure External Route Summarization - Dell PowerConnect B-RX Configuration Manual

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Configuring OSPF

Configure external route summarization

When the BigIron RX 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 BigIron RX 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.
BigIron RX(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.
BigIron RX(config-ospf-router)# show ip ospf config
OSPF Redistribution Address Ranges currently defined:
708 BigIron RX Series Configuration Guide
53-1002253-01