
Configuring IP Services
8-2 117356-A Rev. A
BGP Concepts and Terminology
BGP is an exterior gateway protocol designed to exchange network reachability
information with other BGP systems in other autonomous systems.
BGP exchanges routing information in the form of routing updates that include
the following information:
• Network number
• List of autonomous systems that the routing information has passed through
(the AS path)
• List of path attributes
Figure 8-
1 shows two autonomous systems: AS1 and AS2. Networks within AS1
and AS2 are connected by routers running an interior gateway protocol -- in this
case, OSPF. AS1 and AS2 are connected by routers that run an exterior gateway
protocol -- BGP -- in addition to OSPF.
Figure 8-1. BGP Connecting Autonomous Systems Running OSPF
OSPF/
BGP
OSPF/
BGP
OSPF
OSPF
OSPF
BGP
connection
AS1
AS2
OSPF
OSPF
IP00025A
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