Owner's Manual

Chapter 26. BGP | 697
26
26. BGP
This chapter includes the following sections:
• Overview on page 697
• BGP Features on page 703
Overview
Border gateway protocol (BGP) is an exterior routing protocol that was developed for use in
TCP/IP networks. The primary function of BGP is to allow different autonomous systems (ASs)
to exchange network reachability information.
An AS is a set of routers that are under a single technical administration. This set of routers uses
a different routing protocol, for example Open Shortest Path First (OSPF), for intra-AS routing.
One or more routers in the AS are configured to be border routers, exchanging information with
other border routers (in different ASs) on behalf of all of the intra-routers.
BGP can be used as an exterior border gateway protocol (referred to as EBGP), or it can be
used within an AS as an interior border gateway protocol (referred to as IBGP).
The following sections provide information on how the XCM8800 software supports BGP:
• BGP Four-Byte AS Numbers on page 698
• BGP Attributes on page 698
• BGP Community Attributes on page 699
• Extended Community Attributes on page 699
• Multiprotocol BGP on page 703
For more information on BGP, see the following documents:
• RFC 1771—Border Gateway Protocol version 4 (BGP-4)
• RFC 1965—Autonomous System Confederations for BGP
• RFC 1966—BGP Route Reflection
• RFC 1997—BGP Communities Attribute
• RFC 1745—BGP/IDRP for IP—OSPF Interaction
• RFC 2385—Protection of BGP Sessions via the TCP MD5 Signature Option