336
Chapter 9
BGP Scalability and Advanced Features
you are controlling all the routes in the organization. You can affect routes
and information not only in your organization but in others' as well. If you
have a hub and spoke network, you should first configure the hub as the
route reflector and then configure the routers in the spokes as clients.
You should be especially careful that you know BGP thoroughly if your sys-
tem is a transit AS. A transit AS means that another AS or organization uses
your AS to connect to another AS. Transit ASes are discussed in Chapter 7.
Let's look at an example of configuring RouterA as the route reflector for
the other two routers in autonomous system 100, shown in Figure 9.2.
F I G U R E 9 . 2
A small route reflector configuration
RouterA(config)#router bgp 100
RouterA(config-router)#neighbor 172.16.11.254 remote-as
100
RouterA(config-router)#neighbor 172.16.11.254 route-
reflector-client
RouterA(config-router)#neighbor 172.16.12.254 remote-as
100
RouterA(config-router)#neighbor 172.16.12.254 route-
reflector-client
AS
100
RouterA: 172.16.10.254
RouterB: 172.16.11.254
RouterC: 172.16.12.254
172.16.12.1
172.16.12.254
172.16.11.254
s0
172.16.11.1
s1
s0
s0
RouterA
Concentration Router
eBGP
iBGP
iBGP
eBGP
eBGP
RouterC
RouterB
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