AR28/AR46系列路由器通过BGP的cost属性选择路由典型配置

AR28/AR46系列路由器通过BGP的cost属性选择路由

典型配置

【需求】

所有路由器都配置BGP，AS200中的IGP使用OSPF。路由器A在AS100中，路由器B、路由器C和路由器D在AS200中。路由器A与路由器B和路由器C之间运行EBGP。路由器B和路由器C与路由器D之间运行IBGP。

【组网图】

 

【配置脚本】

RouterA配置脚本

[Router A] interface serial 2/0/0 [Router A-Serial2/0/0] ip address 192.1.1.1 255.255.255.0 [Router A-Serial2/0/0] interface serial 1/0/0 [Router A-Serial1/0/0] ip address 193.1.1.1 255.255.255.0 [Router A] bgp 100 [Router A-bgp] network 1.0.0.0 [Router A-bgp] group ex192 external [Router A-bgp] peer 192.1.1.2 group ex192 as-number 200 [Router A-bgp] group ex193 external [Router A-bgp] peer 193.1.1.2 group ex193 as-number 200 [Router A] acl number 2001 [Router A-acl-basic-2001] rule permit source 1.0.0.0 0.255.255.255 [Router A] route-policy apply_med_50 permit node 10 [Router A-route-policy] if-match acl 2001 [Router A-route-policy] apply cost 50 [Router A] route-policy apply_med_100 permit node 10 [Router A-route-policy] if-match acl 2001 [Router A-route-policy] apply cost 100 [Router A] bgp 100 [Router A-bgp] peer ex193 route-policy apply_med_50 export [Router A-bgp] peer ex192 route-policy apply_med_100 export

RouterB配置脚本

[Router B] interface serial 2/0/0 [Router B-Serial2/0/0] ip address 192.1.1.2 255.255.255.0 [Router B-Serial2/0/0] interface serial 1/0/0 [Router B-Serial1/0/0] ip address 194.1.1.2 255.255.255.0 [Router B] ospf [Router B-ospf-1] import-route bgp [Router B-ospf-1] area 0 [Router B-ospf-1-area-0.0.0.0] network 194.1.1.0 0.0.0.255 [Router B-ospf-1-area-0.0.0.0] network 192.1.1.0 0.0.0.255 [Router B] bgp 200 [Router B-bgp] undo synchronization [Router B-bgp] group ex external [Router B-bgp] peer 192.1.1.1 group ex as-number 100 [Router B-bgp] group in internal [Router B-bgp] peer 194.1.1.1 group in [Router B-bgp] import-route ospf

RouterC配置脚本

[Router C] interface serial 1/0/0 [Router C-Serial1/0/0] ip address 193.1.1.2 255.255.255.0 [Router C-Serial1/0/0] interface serial 2/0/0 [Router C-Serial2/0/0] ip address 195.1.1.2 255.255.255.0 [RouterC] ospf [Router C-ospf-1] import-route bgp [Router C-ospf-1] area 0 [Router C-ospf-1-area-0.0.0.0] network 193.1.1.0 0.0.0.255 [Router C-ospf-1-area-0.0.0.0] network 195.1.1.0 0.0.0.255 [Router C] bgp 200 [Router C-bgp] group ex external [Router C-bgp] peer 193.1.1.1 group ex as-number 100 [Router C-bgp] group in internal [Router C-bgp] peer 195.1.1.1 group in [Router C-bgp] import-route ospf

RouterD配置脚本

[RouterD] interface serial 1/0/0 [RouterD-Serial1/0/0] ip address 194.1.1.1 255.255.255.0 [RouterD-Serial1/0/0] interface serial 2/0/0 [RouterD-Serial2/0/0] ip address 195.1.1.1 255.255.255.0 [RouterD] ospf [Router D-ospf-1] import-route bgp [Router D-ospf-1] area 0 [Router D-ospf-1-area-0.0.0.0] network 194.1.1.0 0.0.0.255 [Router D-osp-1f-area-0.0.0.0] network 195.1.1.0 0.0.0.255 [Router D-ospf-1-area-0.0.0.0] network 4.0.0.0 0.255.255.255 [Router D] bgp 200 [Router D-bgp] group in internal [Router D-bgp] peer 195.1.1.2 group in as-number 200 [Router D-bgp] peer 194.1.1.2 group in as-number 200 [Router D-bgp] import-route ospf

【验证】

1．通过上述配置后，由于路由器C学到的路由1.0.0.0的MED属性比路由器B学到的更小，路由器D优选来自路由器C的路由1.0.0.0。