summary-address (OSPFv2)

Configures route summarization for redistributed routes for an Autonomous System Boundary Router (ASBR).

Syntax

summary-address A.B.C.D E.F.G.H
no summary-address

Command Default

Summary addresses are not configured.

Parameters

A.B.C.D E.F.G.H
IP address and mask for the summary route representing all the redistributed routes in dotted decimal format.

Modes

OSPF router configuration mode

OSPF VRF router configuration mode

Usage Guidelines

Use this command to configure an ASBR 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 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.

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-overflow condition occurs, all aggregate routes and other external routes are flushed out of the AS. When the device exits the external LSDB overflow condition, all the imported routes are summarized according to the configured address ranges.This parameter affects only imported, type 5 external routes.

The no form of the command disables route summarization.

Examples

The following example configures a summary address of 10.1.0.0 with a mask of 10.255.0.0. Summary address 10.1.0.0, 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:

device# configure terminal
device(config)# router ospf
device(config-router-ospf-vrf-default-vrf)# summary-address 10.1.0.0 10.255.0.0