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aggregate-address

This command creates an aggregate by combining the characteristics of multiple routes so that a single route is advertised.

Syntax

aggregate-address prefix/length [summary] [as-set] [summary-and-as-set] [suppress-map route-map] [advertise-map route-map] [attribute-map route-map] [no-reject]
no aggregate-address prefix/length [summary] [as-set] [summary-and-as-set] [suppress-map route-map] [advertise-map route-map] [attribute-map route-map]-map] [no-reject]

Parameters

prefix/length Specifies the prefix and length of the aggregate-address.
summary (Optional) Specifies that BGP will suppress the advertisement of specified routes to all neighbors.
as-set (Optional) Specifies that an aggregate entry AS path attribute contains an AS-SET which includes all the AS numbers contained in the contributor routes.
summary-and-as-set (Optional) Specifies that both the summary and as-set options are enabled for this aggregate.
suppress-map route-map (Optional) Specifies that match clauses for the specified route-map selectively suppress contributor routes from being advertised.
advertise-map route-map (Optional) Specifies that match clauses for the specified route-map selectively advertise contributor routes.
attribute-map route-map (Optional) Specifies that set clauses for the specified route-map set the attributes in the aggregated routes.
no-reject (Optional) Specifies that no route in this aggregation will be rejected.

Defaults

  • If the summary option is not specified, BGP will not suppress the advertisement of the contributor routes to neighbors.
  • If the as-set option is not specified, aggregate entries do not inherit the AS path of the more specific routes in the routing updates.
  • If the summary-and-as-set option is not specified, summary and as-set option settings are used to determine the behavior of those options.
  • If the suppress-map option is not specified, routes specified in the aggregate route are advertised, unless the summary option is specified.
  • If the advertise-map option is not specified, all routes specified in the aggregate route are advertised.
  • If the attribute-map option is not specified, no modifications to the route attributes are made for the aggregate route.
  • If the no-reject option is not specified, aggregated routes that BGP determines may cause potential loops are rejected.

Mode

BGP Router Configuration.

Usage

Route aggregation provides for the aggregating of one or more specific routes into a single aggregate route. Aggregate routes are only created if a more specific route of the aggregate route exists in the BGP routing table.

The summary option creates and advertises the aggregate route while at the same time suppressing the advertisement of all the more specific routes for this aggregate.

The as-set option retains the advertisement of the AS-Path information for the specific routes of the aggregate. The default behavior for an aggregate route is to suppress the AS-Path information for the specific routes of the aggregate. It may be desirable to retain AS-Path information for routes in the aggregate that belong to an AS outside of the AS in which the aggregate is created.

The summary-and-as-set option enables both the summary and as-set options using a single command option.

The suppress-map option creates and advertises an aggregate while at the same time suppressing only those specific routes that match clauses in the specified route-map. Prefixes contained in the aggregate route that are not specifically matched in the route-map are not suppressed. Do not use the suppress-map option in conjunction with the summary option.

The advertise-map option, when used in conjunction with the as-set option, creates and advertises an aggregate, while at the same time allows for specifying in a route-map which AS path information is retained in the aggregate. Do not use the advertise-map option in conjunction with the summary option.

The attribute-map option, creates and advertises an aggregate, while at the same time allows for the modifying of aggregate route attributes specified in the route-map.

Some routes that are members of an aggregation may be rejected to avoid potential loops. Use the no-reject option to no longer reject any routes in the aggregation.

The no aggregate-address command removes the specified aggregate.

Examples

The following example creates and advertises aggregate route 200.51.0.0/22 and suppresses the advertisement of all the more specific routes for this aggregate:

System(su-config)->router bgp 65151
System(su-config-bgp)->aggregate-address 200.51.0.0/22 summary
System(su-config-bgp)->

The following example sets the MED attribute to 50 for routes in aggregate route 200.51.0.0/22 using route-map attrmap1:

System(su-config)->route-map bgp attrmap1 permit 10
System(su-config-route-map-bgp)->set med 50
System(su-config-route-map-bgp)->exit
System(su-config)->show route-map attrmap1
 route-map bgp attrmap1 permit 10
  set med 50
System(su-config)->router bgp 65151
System(su-config-bgp)->aggregate-address 200.51.0.0/22 attribute-map attrmap1
System(su-config-bgp)->

The following example retains AS-path information for routes 200.51.1.0/24 using route-map advmap1 in aggregate route 200.51.0.0/22:

System(su-config)->ip prefix-list advlist1 permit seq 1 200.51.1.0/24
System(su-config)->route-map bgp advmap1
System(su-config-route-map-bgp)->match prefix-list advlist1
System(su-config-route-map-bgp)->exit
System(su-config)->router bgp 65151
System(su-config-bgp)->aggregate-address 200.51.0.0/22 as-set advertise-map advmap1
System(su-config-bgp)->
Published May 2016prev | next

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