、 BGP FUNDAMENTALS e With the exception of the neighbor ebgp-multihop router configuration command, the commands for configuring EBGP&IBGP are the same Within as AS, BGP peers don't need to be directly connected router bgp command enables a bgP routing process and assigns to it a AS number e neighbor remote-as command adds an entry to the bGP neighbor table specifying that the peer identified by a particular ip address belongs to the specified aS for EBGP, neighbor IP address is usually the Ip address directly connected for IBGP, neighbor IP address can be the IP address of any of the router' s interfaces e To verify that bgP peers are up, use the show ip bgp neighbor, if it doesnt show that state=established, then the peers are not up the remote router Id is the highest ip address or highest loopback interface on that router. the table version number increments by new e clear ip bgp to reset the bgp session after make a configuration change INTERNAL BGP 当 BGP speaker收到同一个AS域中其他的 BGP speaker发来的路由信息时 该 BGP speaker只通过EBGP向外部的 BGP speaker发送收到的信息,所以在同 AS域中必须fu1 I meshed loopback interface 当使用某一物理端口作为 neighbor remote-as中的地址时,若该端口不能使 用,则两个路由器将不能连通。使用 loopback interface就没有这一顾虑。 router bgp 100 neighbor 190. 225. 22. 2 remote-as 100 neighbor 190. 225 22.2 update-source loopback 0 neighbor update- source是指明用于连接的是 loopback端口,而不是物 理端口 由于 EBGP peers之间通常是端对端互连的,必须依赖物理端口的连接,因 此较少使用1 borba EXTERNAL BGP ip multihop: 当两个 BGP speaker之间不能直接连接时使用,这时可通过两者的 loopback 端口互连,并使用 neighbor ebgp-multihop,但在配置中必须加上静态路由或起 IGP,以保证两者能互通 loopback interface 0 ip addi ress router bgp 100一、BGP FUNDAMENTALS ⚫ With the exception of the neighbor ebgp-multihop router configuration command,the commands for configuring EBGP&IBGP are the same. ⚫ Within as AS,BGP peers don't need to be directly connected ⚫ router bgp command enables a BGP routing process and assigns to it a AS number ⚫ neighbor remote-as command adds an entry to the BGP neighbor table specifying that the peer identified by a particular IP address belongs to the specified AS. for EBGP ,neighbor IP address is usually the IP address directly connected. for IBGP, neighbor IP address can be the IP address of any of the router's interfaces. ⚫ To verify that BGP peers are up,use the show ip bgp neighbor, if it doesn't show that state=established,then the peers are not up. the remote router ID is the highest ip address or highest loopback interface on that router. the table version number increments by new incoming information ⚫ clear ip bgp to reset the bgp session after make a configuration change INTERNAL BGP 当 BGP speaker 收到同一个 AS 域中其他的 BGP speaker 发来的路由信息时， 该 BGP speaker 只通过 EBGP 向外部的 BGP speaker 发送收到的信息，所以在同 一 AS 域中必须 full meshed loopback interface: 当使用某一物理端口作为 neighbor remote-as 中的地址时，若该端口不能使 用，则两个路由器将不能连通。使用 loopback interface 就没有这一顾虑。 router bgp 100 neighbor 190.225.22.2 remote-as 100 neighbor 190.225.22.2 update-source loopback 0 neighbor update-source 是指明用于连接的是 loopback 端口，而不是物 理端口。 由于 EBGP peers 之间通常是端对端互连的，必须依赖物理端口的连接，因 此较少使用 loopback EXTERNAL BGP ip multihop: 当两个 BGP speaker 之间不能直接连接时使用，这时可通过两者的 loopback 端口互连，并使用 neighbor ebgp-multihop,但在配置中必须加上静态路由或起 IGP，以保证两者能互通。 !Router A loopback interface 0 ip address 129.213.1.1 ! router bgp 100