Chapter 6 Bgp Configuration; Bgp Overview; Introduction To Bgp - H3C S7500 Series Operation Manual

Operation Manual – Routing Protocol
H3C S7500 Series Ethernet Switches

Chapter 6 BGP Configuration

When configuring BGP, go to these sections for information you are interested in:

BGP Overview

BGP Configuration Task List
Displaying and Maintaining BGP Configuration
BGP Configuration Examples
Troubleshooting BGP Configuration
6.1 BGP Overview

6.1.1 Introduction to BGP

Border gateway protocol (BGP) is a dynamic routing protocol designed to be used
between autonomous systems (ASs). An AS is a group of routers that adopt the same
routing policy and belong to the same technical management department.
Four versions of BGP exist: BGP-1 (described in RFC 1105), BGP-2 (described in
RFC 1163), BGP-3 (described in RFC 1267), and BGP-4 (described in RFC 1771). As
the actual Internet exterior routing protocol standard, BGP-4 is widely employed
between Internet service providers (ISPs).
Note:
Unless otherwise noted, BGP in the following sections refers to BGP-4.
BGP has the following features:
Unlike interior gateway protocols (IGPs) such as OSPF (open shortest path first)
and RIP (routing information protocol), BGP is an exterior gateway protocol
(EGP). It does not focus on discovering or calculating routes but controlling the
route propagation and choosing the optimal route.
BGP uses TCP (transport control protocol) as the transport layer protocol (with
the port number being 179) to ensure reliability.
BGP supports classless inter-domain routing (CIDR).
With BGP employed, only the changed routes are propagated. This saves
network bandwidth remarkably and makes it feasible to propagate large amount
of route information across the Internet.
The AS path information used in BGP eliminates route loops thoroughly.
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Chapter 6 BGP Configuration