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CX11x, CX31x, CX710 (Earlier Than V6.03), and CX91x Series Switch Modules V100R001C10 Configuration Guide 12

The documents describe the configuration of various services supported by the CX11x&CX31x&CX91x series switch modules The description covers configuration examples and function configurations.
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Introduction to BGP

Introduction to BGP

This section defines BGP and describes its purpose and benefits.


The Border Gateway Protocol (BGP) is a path vector protocol that allows devices between Autonomous Systems (ASs) to communicate and selects optimal routes. BGP-1 (defined in RFC 1105), BGP-2 (defined in RFC 1163), and BGP-3 (defined in RFC 1267) are three earlier versions of BGP. BGP-4 (defined in RFC 1771) has been used since 1994. Since 2006, unicast IPv4 networks have been using BGP-4 defined in RFC 4271, and other networks (such as IPv6 networks) have been using MP-BGP defined in RFC 4760.

MP-BGP is an extension of BGP-4 and applies to different networks; however, the original message exchange and routing mechanisms of BGP-4 are not changed. MP-BGP applications on IPv6 unicast and IPv4 multicast networks are called BGP4+ and Multicast BGP (MBGP) respectively.


A network is divided into different ASs to facilitate the management over the network. In 1982, the Exterior Gateway Protocol (EGP) was used to dynamically exchange routing information between ASs. EGP advertises only reachable routes but not select optimal routes or prevent routing loops. Therefore, EGP cannot meet network management requirements.

BGP was designed to replace EGP. Different from EGP, BGP can select optimal routes, prevent routing loops, transmit routing information efficiently, and maintain a large number of routes.

Although BGP is used to transmit routing information between ASs, BGP is not the best choice in some scenarios. For example, on the egress connecting a data center to the Internet, static routes instead of BGP are used to prevent a huge number of Internet routes from affecting the data center internal network.


BGP ensures high network security, flexibility, stability, reliability, and efficiency:
Updated: 2019-08-09

Document ID: EDOC1000041694

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