R1#sh run
no ip domain lookup
ip domain name lab.local
ip sla monitor 1
type echo protocol ipIcmpEcho 12.1.1.2 source-ipaddr 12.1.1.1 ## from 12.1.1.1 to 12.1.1.2 是主线路
timeout 100
threshold 2
frequency 2
track 1 ip route 0.0.0.0 0.0.0.0 reachability
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface Serial0/0
ip address 12.1.1.1 255.255.255.0
clock rate 2000000
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface Serial0/1
ip address 13.1.1.1 255.255.255.0
clock rate 2000000
!
ip route 0.0.0.0 0.0.0.0 12.1.1.2 track 1
ip route 0.0.0.0 0.0.0.0 13.1.1.2 10
正常情况下
R1#sh ip route
Gateway of last resort is 12.1.1.2 to network 0.0.0.0
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
12.0.0.0/24 is subnetted, 1 subnets
C 12.1.1.0 is directly connected, Serial0/0
13.0.0.0/24 is subnetted, 1 subnets
C 13.1.1.0 is directly connected, Serial0/1
S* 0.0.0.0/0 [1/0] via 12.1.1.2
当主线路ping不通时候
R1#sh ip route
Gateway of last resort is 13.1.1.2 to network 0.0.0.0
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
13.0.0.0/24 is subnetted, 1 subnets
C 13.1.1.0 is directly connected, Serial0/1
S* 0.0.0.0/0 [10/0] via 13.1.1.2
