3Com Switch 8800 Advanced Software V5 Configuration Guide

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BGP CONFIGURATION
Border Gateway Protocol (BGP) is a dynamic inter-AS route discovery protocol.
When configuring BGP, go to these sections for information you are interested in:
■ “BGP Overview” on page 419
■ “BGP Configuration Task List” on page 434
■ “Configuring BGP Basic Functions” on page 434
■ “Controlling Route Distribution and Reception” on page 436
■ “Configuring BGP Routing Attributes” on page 440
■ “Tuning and Optimizing BGP Networks” on page 442
■ “Configuring a Large Scale BGP Network” on page 444
■ “Displaying and Maintaining BGP Configuration” on page 447
■ “BGP Configuration Examples” on page 448
■ “Troubleshooting BGP Configuration” on page 467
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The term "router" refers to a router in a generic sense or a Layer 3 switch, and
BGP refers to BGP-4 in this document.
BGP Overview Three early versions of BGP are BGP-1 (RFC1105), BGP-2 (RFC1163) and BGP-3
(RFC1267). The current version in use is BGP-4 (RFC1771). BGP-4 is rapidly
becoming the defacto Internet exterior routing protocol standard and is commonly
used between ISPs.
The characteristics of BGP are as follows:
■ Focusing on the control of route propagation and the selection of optimal
routes rather than the discovery and calculation of routes, which makes BGP,
an exterior routing protocol different from interior routing protocols such as
OSPF and RIP
■ Using TCP as its transport layer protocol to enhance reliability
■ Supporting CIDR
■ Substantially reducing bandwidth occupation by advertising updating routes
only and applicable to advertising a great amount of routing information on
the Internet
■ Eliminating route loops completely by adding AS path information to BGP
routes