Selective aggregation means that when routes are aggregated in BGP, some pre-aggregation routes are selected and advertised together with the aggregated routes, rather than all or nothing, where all pre-aggregation routes are sent or none at all.

This section describes the suppress-map option of the aggregate-address command for selective aggregation. suppress-map option allows you to determine the pre-aggregation routes that are not advertised.

aggregate-address command : suppress-map option

Selective aggregation with the suppress-map option is considered on the basis that all default pre-aggregation routes are advertised. The suppress-map option allows you to stop some of the pre-aggregation routes from being advertised along with the aggregation routes.

Figure: Selective Aggregation with suppress-map
Figure: Selective Aggregation with suppress-map

The syntax of the support-map command is as follows.

aggregate-address suppress-map

(config)#router bgp <AS>
(config-router)#aggregate-address <network-address> <subnetmask> suppress-map <route-map-name>

<AS>: AS number
<network-address>: Network address of the aggregate route
<subnetmask>: Subnet mask of the aggregate route
<route-map-name>: route-map name

Note that the route map is specified after suppress-map, but it is easy to get confused with the route map configuration suppress-map is an option to “stop” the pre-aggregation routes. Therefore, the pre-aggregation routes that are permit in the route-map after suppress-map are no longer advertised. Conversely, pre-aggregation routes that you want to advertise along with the aggregation route are configured to be denied in the route-map.

Selective aggregation with suppress-map configuration example

Consider the specific configuration in “Figure: Selective Aggregation with suppress-map”. Generate an aggregate route that aggregates the following four BGP routes.


Aggregating these four routes with the longest subnet mask is “”. Along with this aggregate route, “” and “” are also advertised. In other words, stop advertising and of the pre-aggregation route. The configuration of the suppress-map is as follows.

suppress-map configuration example

access-list 1 permit
access-list 1 permit
route-map SUPP-MAP permit 10
 match ip address 1
router bgp 
 aggregate-address suppress-map SUPP-MAP

The routes matching the sequence 10 match condition in the route-map “SUPP-MAP” are and Since the route map SUPP-MAP is specified in suppress-map, and advertisements will be suppressed.

The route map “SUPP-MAP” still has an implicit deny any at the end.と192.168.3.0/24. Therefore, the advertisement of these two pre-aggregation routes will not be suppressed and will be advertised to the neighbor along with the aggregate route.

set action is not required for route-map specified the suppress-map.

Figure: suppress-map configuration example
Figure: suppress-map configuration example

And note the BGP table when suppress-map is configured. If you suppress the advertisement of a particular pre-aggregation route with suppress-map, the BGP table will be a mixture of “*(valid)” and “s(suppressed)”.

BGP table when suppress-map is configured

R1#sh ip bgp 
BGP table version is 8, local router ID is
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*>                            32768 i
s>                  0         32768 i
*>                  0         32768 i
s>                  0         32768 i
*>                  0         32768 i



  • suppress-map is an option to the aggregate-address command to perform selective aggregation. suppress-map performs selective aggregation for all neighbors.
  • Specify a route-map after suppress-map. Routes that are permited in the route map are not advertised as suppressed.