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Minimal Configuration

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static Static routes

traffic-engineering Traffic engineered routes

RouterA(config)#router bgp ?

<1-65535> Autonomous system number

RouterA(config)#router bgp 34000

RouterA(config-router)#

So far, we have configured the router with the autonomous system num-

ber (ASN) to which it belongs. Next, we must add network statements to
identify the networks that the router must propagate information to in order
for another AS to learn about ours. We are using network statements to
avoid redistribution from an IGP into BGP, which is not recommended. The
network statement establishes those address ranges to be advertised, such as
those learned by the IGPs running in the network. It will not actually adver-
tise anything until peering is established or the route to be advertised is
reachable by the advertising router, meaning that a route makes its way into
the routing table.

When taking the exam, you may need to know what a peer group is. A peer

group is a way of defining a template containing parameters that more than

one peer will use. This becomes useful when many different neighbors use

identical outbound routing policies, which will be discussed in Chapter 9. The

parameters set by a peer group affect only the outbound parameters, and the

inbound parameters can be configured differently. This can simplify the con-

figuration, as updates need to occur only once. BGP peer configurations will

not be discussed in this course.

The next step is to identify peers. In BGP, as opposed to IGPs, with the

exception of certain OSPF configurations, you must explicitly specify the IP
addresses of the routers with which you want to exchange information.
Internal peers will have the same ASN used in the source router's router
bgp

command. External peers are those with a different AS from the AS

defined on the source router. Let's look at the command and the syntaxes:

neighbor

address remote-as autonomous-system-number

The address is the IP address of the neighboring (peer) router. It can be

the loopback address or the directly connected IP address. The autonomous-
system-number

is the peer's ASN. An iBGP peer will have the same ASN as

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