BGP学习精华

来源： 作者： 出处：巧巧读书 2006-07-25 进入讨论组

• 关 键 词：
• loopback
• router
• update
• 配置

　　EBGP and IBGP
　　　 Enabling BGP routing
　　The command used to enable BGP on a router is:
　　router bgp autonomous-system
　　RTA#
　　router bgp 100
　　RTB#
　　router bgp 200
　　The above statements indicate that RTA is running BGP and it belongs to
　　AS100 and RTB is running BGP and it belongs to AS200 and so on.
　　BGP Neighbors/Peers
　　The neighbor command used to establish a TCP connection is:
　　neighbor ip-address remote-as number
　　The remote-as number is the AS number of the router we are trying to
　　connect to via BGP.
　　The ip-address is the next hop directly connected address for EBGP1 and
　　any IP address2 on the other router for IBGP.
　　clear ip bgp address (where address is the neighbor address)
　　clear ip bgp * (clear all neighbor connections)
　　
　　By default, BGP sessions begin using BGP Version 4 and negotiating
　　downward to earlier versions if necessary. To prevent negotiations and
　　force the BGP version used to communicate with a neighbor, perform the
　　following task in router configuration mode:
　　neighbor { ip address| peer-group-name} version value
　　An example of the neighbor command configuration follows:
　　　
　　RTA#
　　router bgp 100
　　neighbor 129.213.1.1 remote-as 200
　　RTB#
　　router bgp 200
　　neighbor 129.213.1.2 remote-as 100
　　neighbor 175.220.1.2 remote-as 200
　　RTC#
　　router bgp 200
　　neighbor 175.220.212.1 remote-as 200
　　BGP and Loopback interfaces
　　Using a loopback interface to define neighbors is commonly used with IBGP
　　rather than EBGP. Normally the loopback interface is used to make sure
　　that the IP address of the neighbor stays up and is independent of an
　　interface that might be flaky. In the case of EBGP, most of the time the
　　peer routers are directly connected and loopback does not apply.
　　If the IP address of a loopback interface is used in the neighbor command,
　　some extra configuration needs to be done on the neighbor router.
　　The neighbor router needs to tell BGP that it is using a loopback
　　interface rather than a physical interface to initiate the BGP neighbor
　　TCP connection. The command used to indicate a loopback interface is:
　　neighbor ip-address update-source interface
　　The following example should illustrate the use of this command.
　　　
　　RTA#
　　router bgp 100
　　neighbor 190.225.11.1 remote-as 100
　　neighbor 190.225.11.1 update-source loopback 1
　　RTB#
　　router bgp 100
　　neighbor 150.212.1.1 remote-as 100
　　
　　RTA#
　　router bgp 100
　　neighbor 180.225.11.1 remote-as 300
　　neighbor 180.225.11.1 ebgp-multihop
　　RTB#
　　router bgp 300
　　neighbor 129.213.1.2 remote-as 100
　　
　　//关于BGP and loopback interfaces中的配置实例中：
　　RTA#
　　router bgp 100
　　neighbor 190.225.11.1 remote-as 100
　　neighbor 190.225.11.1 update-source int loopback 1
　　应是：
　　neighbor 190.225.11.1 update-source loopback 1URl收藏 http://www.qqread.com/net-manage/o338176081.html 更多内容请看BGP协议专题，或进入讨论组讨论。

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