1. VPN站点内配置IP地址
[PE-GigabitEthernet0/0/0]ip add 10.1.1.1 24
[PE-GigabitEthernet0/0/2]ip add 10.2.1.1 24
[CE1-GigabitEthernet0/0/0]ip add 10.1.1.2 24
[CE1-GigabitEthernet0/0/1]ip add 10.3.1.2 24
[CE2-GigabitEthernet0/0/0]ip add 10.2.1.3 24
[CE2-GigabitEthernet0/0/1]ip add 10.4.1.3 24
[AR4-LoopBack1]ip add 4.4.4.4 32
[AR4-GigabitEthernet0/0/0]ip add 10.3.1.4 24
[AR4-GigabitEthernet0/0/1]ip add 10.4.1.4 24
2. VPN站点内配置OSPF，使得AR4的Loopback接口路由可以发送到CE1，CE2
[CE1]ospf 1
[CE1-ospf-1]area 0
[CE1-ospf-1-area-0.0.0.0]network 10.1.1.0 0.0.0.255
[CE1-ospf-1-area-0.0.0.0]network 10.3.1.0 0.0.0.255
[CE2]ospf 1
[CE2-ospf-1]area 0
[CE2-ospf-1-area-0.0.0.0]network 10.2.1.0 0.0.0.255
[CE2-ospf-1-area-0.0.0.0]network 10.4.1.0 0.0.0.255
[AR4]ospf 1
[AR4-ospf-1]area 0
[AR4-ospf-1-area-0.0.0.0]network 4.4.4.4 0.0.0.0
[AR4-ospf-1-area-0.0.0.0]network 10.3.1.0 0.0.0.255
[AR4-ospf-1-area-0.0.0.0]network 10.4.1.0 0.0.0.255
3. 在PE上配置VPN实例及OSPF多实例
[PE]ip vpn-instance vpn1
[PE-vpn-instance-vpn1]ipv4-family
[PE-vpn-instance-vpn1-af-ipv4] route-distinguishe 100:1
[PE-vpn-instance-vpn1-af-ipv4]vpn-target 1:1
[PE-GigabitEthernet0/0/0]ip binding vpn-instance vpn1
[PE-GigabitEthernet0/0/0]ip add 10.1.1.1 24
[PE-GigabitEthernet0/0/1]ip binding vpn-instance vpn1
[PE-GigabitEthernet0/0/1]ip add 10.2.1.1 24
[PE]ospf vpn-instance vpn1 //配置OSPF多实例
[PE-ospf-1]area 0
[PE-ospf-1-area-0.0.0.0]network 10.1.1.0 0.0.0.255
[PE-ospf-1-area-0.0.0.0]network 10.2.1.0 0.0.0.255
4. 配置OSPF接口的Cost值,
[PE-GigabitEthernet0/0/1]ospf cost 100 //在PE的g0/0/1配置Cost值，使OSPF优选链路CE1
[AR4-GigabitEthernet0/0/1]ospf cost 100
5. 配置路由策略, 配置备份下一跳和备份出接口。同时配置if-match项，限制应用范围。
[PE]ip ip-prefix f1 permit 4.4.4.4 32
[PE]route-policy f1 permit node 10
[PE-route-policy]if-match ip-prefix f1
[PE-route-policy]apply backup-nexthop 10.2.1.3
[PE-route-policy]apply backup-interface g0/0/1
6. 配置BFD与IP FRR联动
[PE]bfd
[PE]bfd f1 bind peer-ip 10.1.1.2 vpn-instance vpn1 interface g0/0/0
[PE-bfd-session-f1]discriminator local 10
[PE-bfd-session-f1]discriminator remote 20
[PE-bfd-session-f1]commit
[CE1]bfd
[CE1]bfd f1 bind peer-ip 10.1.1.1 interface g0/0/0
[CE1-bfd-session-f1]discriminator local 20
[CE1-bfd-session-f1]discriminator remote 10
[CE1-bfd-session-f1]commit
7. 使能私网IP FRR功能
[PE]ip vpn-instance vpn1
[PE-vpn-instance-vpn1]ipv4-family
[PE-vpn-instance-vpn1-af-ipv4]ip frr route-policy f1
8. 检查配置
看到PE上到4.4.4.4/32的路由下一跳为10.1.1.2，且有备份下一跳、备份出接口
[CE1-GigabitEthernet0/0/1]shutdown
