BGP 负载共享

详细解析配置BGP负载共享（二）

2.      单台边界路由器多宿主末端网络连接到单一ISP环境中的负载共享

　　本场景展示了当在远程AS和本地AS之间存在多条链路时如何完成负载共享。链路建立在本地AS中的一个路由器和远程AS中的多个路由器之间。

　　top图如下：

 

默认情况下BGP只从可能存在的等价路径中选择出一条最佳的路径，通过命令maximum-path对可选择的等价路径数目（1~6）进行修改。

　　配置如下：

RouterA

RouterA (config)#int s1/0 RouterA (config-if)#ip add 160.20.20.1 255.255.255.0 RouterA (config-if)#no sh RouterA (config)#int s1/2 RouterA (config-if)#ip add 150.10.10.1 255.255.255.0 RouterA (config-if)#no sh RouterA (config-if)#int lo0 RouterA (config-if)#ip add 1.1.1.1 255.255.255.0 RouterA (config-if)#router bgp 11 RouterA (config-router)#network 1.0.0.0 RouterA (config-router)#neighbor 150.10.10.2 remote-as 10 RouterA (config-router)#neighbor 160.20.20.2 remote-as 10 RouterA (config-router)#maximum-paths 2

RouterB

RourterB(config)#int s1/2 RourterB(config-if)#ip add 160.20.20.2 255.255.255.0 RourterB(config-if)#no sh RourterB(config-if)#int fa0/0 RourterB(config-if)#ip add 2.2.2.1 255.255.255.0 RourterB(config-if)#no sh RourterB(config)#router bgp 10 RourterB(config-router)#network 2.0.0.0 RourterB(config-router)#neighbor 160.20.20.1 remote-as 11 RourterB(config-router)#auto-summary

RouterC

RourterB(config)#int s1/2 RourterB(config-if)#ip add 150.10.10.2 255.255.255.0 RourterB(config-if)#no sh RourterB(config-if)#int fa0/0 RourterB(config-if)#ip add 2.2.2.2 255.255.255.0 RourterB(config-if)#no sh RourterB(config)#router bgp 10 RourterB(config-router)#network 2.0.0.0 RourterB(config-router)#neighbor 150.10.10.1 remote-as 11 RourterB(config-router)#auto-summary

　　验证：

RouterA# sh ip bgp BGP table version is 5, local router ID is 1.1.1.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> 1.0.0.0 0.0.0.0 0 32768 i *> 2.0.0.0 160.20.20.2 0 0 10 i * 150.10.10.2 0 0 10 i RouterA#sh ip ro Gateway of last resort is not set 1.0.0.0/24 is subnetted, 1 subnets C 1.1.1.0 is directly connected, Loopback0 B 2.0.0.0/8 [20/0] via 150.10.10.2, 00:16:32 [20/0] via 160.20.20.2, 00:15:47 160.20.0.0/24 is subnetted, 1 subnets C 160.20.20.0 is directly connected, Serial1/0 150.10.0.0/24 is subnetted, 1 subnets C 150.10.10.0 is directly connected, Serial1/2 RouterA# RouterA#traceroute 2.2.2.2 Type escape sequence to abort. Tracing the route to 2.2.2.2 1 150.10.10.2 64 msec 160.20.20.2 92 msec *