Juniper BGP - CONFIGURATION GUIDE V 11.1.X Configuration Manual page 97

passed along to router SanJose and preserved when the aggregate route is created.
As a result, the aggregate route is not advertised outside the AS. The following
commands demonstrate how to configure router SanJose to prevent the aggregate
from not being advertised:
aggregate-address
NOTE: Do not use the as-set keyword when you have many paths to aggregate. If
you do, the aggregated route is continually withdrawn and reupdated as AS-path
reachability information changes for the summarized routes.
NOTE: If you want to suppress advertisements only to certain neighbors, you
can with caution use the neighbor distribute-list command. If a more specific
route leaks out, all BGP speakers will prefer that route over the less specific aggregate
you are generating (using longest-match routing).
host2(config)#router bgp 873
host2(config-router)#neighbor 10.2.2.3 remote-as 873
host2(config-router)#neighbor 10.5.5.1 remote-as 17
host2(config-router)#network 172.24.24.0 mask 255.255.248.0
host2(config-router)#aggregate-address 172.24.0.0 255.255.224.0 attribute-map
conf_agg_att
host2(config-router)#exit
host2(config)#route-map conf_agg_att permit 10
host2(config-route-map)#set community no-export
Use to create an aggregate entry in a BGP routing table that summarizes more
specific routes.
For IPv4 routes, you must specify an aggregate IP address (address) and aggregate
IP mask (mask). For IPv6 routes, you must specify an aggregate IPv6 prefix
(ipv6Prefix).
The optional as-set keyword preserves path information by creating an AS-Set
that contains all the AS numbers traversed by the aggregated routes.
The summary-only keyword advertises only the aggregate route; it suppresses
the advertisement of all more specific routes. Contrast with the suppress-map
keyword.
The suppress-map keyword enables you to specify a route map to filter particular
routes covered by the aggregate that will be suppressed. Contrast with the
summary-only keyword.
The advertise-map keyword enables you to specify the advertise-map-tag, a
string of up to 32 characters that identifies the route map that sets the routes to
create AS-Set origin communities.
The attribute-map keyword enables you to specify the attribute-map-tag, a
string of up to 32 characters that identifies the route map that sets the attributes
of the aggregate route.
Chapter 1: Configuring BGP Routing
Advertising Routes
61