Cisco Systems 78-11741-02 BGP Aggregate Route Examples, BGP Community with Route Maps Examples

Configuring BGP

BGP Configuration Examples

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-setkeyword in the aggregate-addressrouter 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

Cisco IOS IP Configuration Guide

IPC-341