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Chapter 7
BGP's Basic Components
BGP peers, which are two routers running BGP and connecting
through a TCP session to exchange messages. BGP peering is a refer-
ence to a specific relationship at the policy level, which will be covered
in more detail in Chapter 8.
The differences between Internal BGP and External BGP.
The differences between distance-vector protocols and link-state rout-
ing protocols. Link-state routing protocols (or a hybrid of link-state
routing and distance-vector) provide for greater scalability and stabil-
ity.
When to use BGP and when not to use BGP.
Ingress filtering, which filters BGP messages and announcements
based on the source address and an administrative range.
BGP message types identified in the BGP common header, which are
the OPEN, UPDATE, NOTIFICATION, and KEEPALIVE message
types.
BGP path attributes associated with the UPDATE message type.
BGP should be used only when a network meets a few specific criteria, as
outlined in this chapter. In Chapter 8, we'll look at how BGP works, how the
BGP metrics are used, how to change the metrics, as well as how to con-
figure BGP.
Key Terms
Before taking the exam, make sure you're familiar with the following terms:
Active state
AGGREGATOR
ATOMIC_AGGREGATE
autonomous system
AS_PATH
COMMUNITIES
Connection state
Established state
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