attribute is not set for the aggregated route. The following commands configure router
SanJose to aggregate the routes while preserving the path information:
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 summary-only as-set
If you do not want to aggregate all more specific routes, you can use a route map to limit
aggregation. Consider Figure 17 on page 59 again. Suppose you do not want router SanJose
to aggregate prefix 172.24.48.0/20. The following commands show how you can configure
a route map on router SanJose to match this prefix, and how to invoke the route map
with the advertise-map option:
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)#neighbor 10.2.2.3 route-map lmt_agg in
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 advertise-map lmt_agg
host2(config-router)#exit
host2(config)#route-map lmt_agg permit 10
host2(config-route-map)#match ip address 1
host2(config-route-map)#exit
host2(config)#access-list 1 permit 172.24.48.0 0.240.255.255
You can use the attribute-map option to configure attributes for the aggregated route.
In Figure 17 on page 59, suppose that router LA has been configured to set the community
attribute for route 172.24.160.0/19 to no-export. This attribute is 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:
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
aggregate-address
• 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.
Copyright © 2010, Juniper Networks, Inc.60
JunosE 11.2.x BGP and MPLS Configuration Guide
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