Concept Guide

Suppressing BGP aggregate routes
The routes that are suppressed are not advertised to any of the BGP neighbors. You can suppress the aggregate routes using the
suppress-map or summary-only options in the aggregate-address conguration. To suppress the advertisement of the
aggregate routes using BGP, use the following commands.
• Create an aggregate entry and suppress the advertisement of specic routes to all neighbors.
CONFIG-ROUTER-BGP mode
aggregate—address address-mask summary-only
• Create an aggregate entry and suppress the advertisement of specic routes.
CONFIG-ROUTER-BGP mode
aggregate—address address-mask suppress-map map-name
The suppress-map keyword creates the aggregate route but suppress the advertisement of specied routes. The routes that are
suppressed are not advertised to the neighbors. You can use match clause of route maps to selectively suppress the specic route
from the aggregate routes.
Example of suppressing aggregate routes using BGP
Following is the sample conguration to suppress the advertisement of specic aggregate routes.
DellEMC# configure terminal
DellEMC(conf)# router bgp 100
DellEMC(conf-router_bgp)# aggregate-address 10.1.1.0/24 suppress-map map1
DellEMC(conf-router_bgp)# exit
DellEMC(conf)#
The route-map named map1 can have any action such as permit and sequence number congured, so that the advertisement of
aggregate routes can be suppressed based on the set action in the route-map.
Following is the sample conguration to suppress the advertisement of specic aggregate routes to all neighbors.
DellEMC# configure terminal
DellEMC(conf)# router bgp 100
DellEMC(conf-router_bgp)# aggregate-address 10.1.1.0 255.255.255.0 summary-only
DellEMC(conf-router_bgp)# exit
DellEMC(conf)#
Filtering BGP
The following section describes the methods used to lter the updates received from BGP neighbors.
Following are the ltering methods of BGP updates:
• Filtering using IP prex lists
• Filtering using route maps
• Filtering using AS-PATH information
• Filtering using community lists
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Border Gateway Protocol (BGP)