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Configuring BGP
BGP Configuration Examples
IPC-341
Cisco IOS IP Configuration Guide
BGP Aggregate Route Examples
The following examples show how you can use aggregate routes in BGP either by redistributing an
aggregate route into BGP or by using the BGP Conditional Aggregate routing feature.
In the following example, the redistribute static router configuration command is used to redistribute
aggregate route 193.0.0.0:
ip route 193.0.0.0 255.0.0.0 null 0
!
router bgp 100
redistribute static
The following configuration shows how to create an aggregate entry in the BGP routing table when at
least one specific route falls into the specified range. The aggregate route will be advertised as coming
from your autonomous system and has the atomic aggregate attribute set to show that information might
be missing. (By default, atomic aggregate is set unless you use the as-set keyword in the
aggregate-address router configuration command.)
router bgp 100
aggregate-address 193.0.0.0 255.0.0.0
The following example shows how to create an aggregate entry using the same rules as in the previous
example, but the path advertised for this route will be an AS_SET consisting of all elements contained
in all paths that are being summarized:
router bgp 100
aggregate-address 193.0.0.0 255.0.0.0 as-set
The following example shows how to create the aggregate route for 193.0.0.0 and also suppress
advertisements of more specific routes to all neighbors:
router bgp 100
aggregate-address 193.0.0.0 255.0.0.0 summary-only
BGP Community with Route Maps Examples
This section contains three examples of the use of BGP communities with route maps, and two examples
that also contain confederation configurations. For an example of how to configure a BGP confederation,
see the section “BGP Confederation Examples” in this chapter.
The first example shows how the route map named set-community is applied to the outbound updates to
the neighbor 171.69.232.50. The routes that pass access list 1 have the special community attribute value
no-export. The remaining routes are advertised normally. This special community value automatically
prevents the advertisement of those routes by the BGP speakers in autonomous system 200.
router bgp 100
neighbor 171.69.232.50 remote-as 200
neighbor 171.69.232.50 send-community
neighbor 171.69.232.50 route-map set-community out
!
route-map set-community 10 permit
match address 1
set community no-export
!
route-map set-community 20 permit
match address 2