.1、拓扑图
链接：https://pan.baidu.com/s/19_s-uZZc-Q0lezFDNv77zw
提取码：8888
eNSP
链接：https://pan.baidu.com/s/1wP0vHim4yqVV0bc0wmzhFw
提取码：8888

R1与R2之间存在两条链路。其中双方的S0/0/0接口通过一条低带宽链路互联，IP地址段为192.168.11.0/24；另外双方的GE0/0/3接口通过另一条线路互联IP地址段为192.168.12.0/24。

2.网络需求
完成R1及R2的配置，使得网络正常时PC1与PC2互访的流量走链路2。当链路2发生故障时，PC1与PC2互访的流量要能够自动切换到链路1。
3.R1的配置
display current-configuration

sysname R1

bfd

interface Serial0/0/0
link-protocol ppp
ip address 192.168.11.1 255.255.255.0

interface GigabitEthernet0/0/0
ip address 192.168.10.254 255.255.255.0

interface GigabitEthernet0/0/1

interface GigabitEthernet0/0/2

interface GigabitEthernet0/0/3
ip address 192.168.12.1 255.255.255.0

wlan

interface NULL0

bfd bfd12 bind peer-ip 192.168.12.2
discriminator local 1
discriminator remote 2
commit

ip route-static 192.168.20.0 255.255.255.0 192.168.12.2 track bfd-session bfd12
ip route-static 192.168.20.0 255.255.255.0 192.168.11.2 preference 90

return

4.R2的配置
display current-configuration

sysname R2

bfd

interface Serial0/0/0
link-protocol ppp
ip address 192.168.11.2 255.255.255.0

interface GigabitEthernet0/0/0
ip address 192.168.20.254 255.255.255.0

interface GigabitEthernet0/0/1

interface GigabitEthernet0/0/2

interface GigabitEthernet0/0/3
ip address 192.168.12.2 255.255.255.0

wlan

interface NULL0

bfd bfd12 bind peer-ip 192.168.12.1
discriminator local 2
discriminator remote 1
commit

ip route-static 192.168.10.0 255.255.255.0 192.168.12.1 track bfd-session bfd12
ip route-static 192.168.10.0 255.255.255.0 192.168.11.1 preference 90

return

5.查看一下R1的路由表

6.当R1的g0/0/3端口shutdown时，数据自动从链路1转发，当R1的g0/0/3端口undo shutdown时，则从链路2转发。