浮动静态路由
浮动静态路由是一种特殊的静态路由，通过配置一个比主路由的管理距离更大的静态路由，保证网络中主路由失效的情况下，提供备份路由。但在主路由存在的情况下备份路由不会出现在路由表中。
拓扑图
VPC1和VPC2通信，默认走上面R2—R1—R3—PC2路由，如果R1挂掉或者端口down，会自动切换到下面R2—R4—R3路由。
配置名称和IP地址
R1
Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Routerconfig)#hostname R1
R1config)#interface ethernet 0/0
R1config-if)#ip add 12.1.1.1 255.255.255.0
R1config-if)#no shut
R1config)#interface ethernet 0/1
R1config-if)#ip add 13.1.1.1 255.255.255.0
R1config-if)#no shu
R1#show ip interface bri
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 12.1.1.1 YES manual up up
Ethernet0/1 13.1.1.1 YES manual up up
Ethernet0/2 unassigned YES manual administratively down down
Ethernet0/3 unassigned YES NVRAM administratively down down
R1#
R2
Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Routerconfig)#hostname R2
R2config)#interface ethernet 0/1
R2config-if)#ip add 12.1.1.2 255.255.255.0
R2config-if)#no shut
R2config)#interface e
R2config)#interface ethernet 0/2
R2config-if)#ip add 172.16.1.1 255.255.255.0
R2config-if)#no shut
R2config)#interface ethernet 0/0
R2config-if)#ip add 24.1.1.1 255.255.255.0
R2config-if)#no shut
R2#show ip interface brief
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 24.1.1.1 YES manual up up
Ethernet0/1 12.1.1.2 YES manual up up
Ethernet0/2 172.16.1.1 YES manual up up
Ethernet0/3 unassigned YES unset administratively down down
R2#
R3
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Routerconfig)#hostname R3
R3config)#interface ethernet 0/0
R3config-if)#ip add 13.1.1.3 255.255.255.0
R3config-if)#no shu
R3config)#interface
*Jul 8 23:17:56.567: %LINK-3-UPDOWN: Interface Ethernet0/0, changed state to up
*Jul 8 23:17:57.576: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0/0, chan
ged state to up
R3config)#interface ethernet 0/1
R3config-if)#ip add 34.1.1.3 255.255.255.0
R3config-if)#no shut
R3config)#interface ethernet 0/2
R3config-if)#ip add 172.16.2.1 255.255.255.0
R3config-if)#no shut
R3config-if)#en
*Jul 8 23:19:13.080: %LINK-3-UPDOWN: Interface Ethernet0/2, changed state to up
*Jul 8 23:19:14.080: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0/2, chan
ged state to up
R3config-if)#end
R3#
*Jul 8 23:19:15.186: %SYS-5-CONFIG_I: Configured from console by console
R3#show ip interface brief
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 13.1.1.3 YES manual up up
Ethernet0/1 34.1.1.3 YES manual up up
Ethernet0/2 172.16.2.1 YES manual up up
Ethernet0/3 unassigned YES unset administratively down down
R3#
R4
Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Routerconfig)#hostname R4
R4config)#interface ethernet 0/0
R4config-if)#ip add 24.1.1.4 255.255.255.0
R4config-if)#no shu
R4config)#interface ethernet 0/1
R4config-if)#ip address 34.1.1.4 255.255.255.0
R4config-if)#no shut
R4#show ip interface brief
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 24.1.1.4 YES manual up up
Ethernet0/1 34.1.1.4 YES manual up up
Ethernet0/2 unassigned YES unset administratively down down
Ethernet0/3 unassigned YES unset administratively down down
Ethernet1/0 unassigned YES unset administratively down down
Ethernet1/1 unassigned YES unset administratively down down
Ethernet1/2 unassigned YES unset administratively down down
Ethernet1/3 unassigned YES unset administratively down down
R4#
VPC1
VPCS> set pcname VPC1
VPC1> ip 172.16.1.2/24 172.16.1.1
Checking for duplicate address...
PC1 : 172.16.1.2 255.255.255.0 gateway 172.16.1.1
VPC1> ping 172.16.1.1
172.16.1.1 icmp_seq=1 timeout
84 bytes from 172.16.1.1 icmp_seq=2 ttl=255 time=0.532 ms
84 bytes from 172.16.1.1 icmp_seq=3 ttl=255 time=0.447 ms
84 bytes from 172.16.1.1 icmp_seq=4 ttl=255 time=0.386 ms
84 bytes from 172.16.1.1 icmp_seq=5 ttl=255 time=0.470 ms
VPC1>
VPC2
VPCS> set pcname VPC2
VPC2> ip 172.16.2.2/24 172.16.2.1
Checking for duplicate address...
PC1 : 172.16.2.2 255.255.255.0 gateway 172.16.2.1
VPC2> ping 172.16.2.1
84 bytes from 172.16.2.1 icmp_seq=1 ttl=255 time=0.305 ms
84 bytes from 172.16.2.1 icmp_seq=2 ttl=255 time=0.887 ms
84 bytes from 172.16.2.1 icmp_seq=3 ttl=255 time=0.548 ms
84 bytes from 172.16.2.1 icmp_seq=4 ttl=255 time=0.600 ms
84 bytes from 172.16.2.1 icmp_seq=5 ttl=255 time=0.503 ms
VPC2>
配置完IP地址，最好互相ping下直接路由，避免是因为IP地址产生的问题。
配置静态路由和浮动静态路由
R1
R1config)#ip route 172.16.1.0 255.255.255.0 ethernet 0/0 12.1.1.2
R1config)#ip route 172.16.2.0 255.255.255.0 ethernet 0/1 13.1.1.3
R1config)#
R1#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 12.1.1.0/24 is directly connected, Ethernet0/0
L 12.1.1.1/32 is directly connected, Ethernet0/0
13.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 13.1.1.0/24 is directly connected, Ethernet0/1
L 13.1.1.1/32 is directly connected, Ethernet0/1
172.16.0.0/24 is subnetted, 2 subnets
S 172.16.1.0 [1/0] via 12.1.1.2, Ethernet0/0
S 172.16.2.0 [1/0] via 13.1.1.3, Ethernet0/1
R1#
R2
R2config)#ip route 0.0.0.0 0.0.0.0 ethernet 0/1 12.1.1.1
R2config)#ip route 0.0.0.0 0.0.0.0 ethernet 0/0 24.1.1.4 ?
<1-255> Distance metric for this route
multicast multicast route
name Specify name of the next hop
permanent permanent route
tag Set tag for this route
track Install route depending on tracked item
R2config)#ip route 0.0.0.0 0.0.0.0 ethernet 0/0 24.1.1.4 10
R2#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is 12.1.1.1 to network 0.0.0.0
S* 0.0.0.0/0 [1/0] via 12.1.1.1, Ethernet0/1
12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 12.1.1.0/24 is directly connected, Ethernet0/1
L 12.1.1.2/32 is directly connected, Ethernet0/1
24.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 24.1.1.0/24 is directly connected, Ethernet0/0
L 24.1.1.1/32 is directly connected, Ethernet0/0
172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.16.1.0/24 is directly connected, Ethernet0/2
L 172.16.1.1/32 is directly connected, Ethernet0/2
R2#
#参数10这个取值范围为1-255之间，
R3
R3config)#ip route 0.0.0.0 0.0.0.0 ethernet 0/0 13.1.1.1
R3config)#ip route 0.0.0.0 0.0.0.0 ethernet 0/1 34.1.1.4 10
R3#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is 13.1.1.1 to network 0.0.0.0
S* 0.0.0.0/0 [1/0] via 13.1.1.1, Ethernet0/0
13.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 13.1.1.0/24 is directly connected, Ethernet0/0
L 13.1.1.3/32 is directly connected, Ethernet0/0
34.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 34.1.1.0/24 is directly connected, Ethernet0/1
L 34.1.1.3/32 is directly connected, Ethernet0/1
172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.16.2.0/24 is directly connected, Ethernet0/2
L 172.16.2.1/32 is directly connected, Ethernet0/2
R3#
R4
R4config)#ip route 172.16.1.0 255.255.255.0 ethernet 0/0 24.1.1.2
R4config)#ip route 172.16.2.0 255.255.255.0 ethernet 0/1 34.1.1.3
R4#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
24.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 24.1.1.0/24 is directly connected, Ethernet0/0
L 24.1.1.4/32 is directly connected, Ethernet0/0
34.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 34.1.1.0/24 is directly connected, Ethernet0/1
L 34.1.1.4/32 is directly connected, Ethernet0/1
172.16.0.0/24 is subnetted, 2 subnets
S 172.16.1.0 [1/0] via 24.1.1.2, Ethernet0/0
S 172.16.2.0 [1/0] via 34.1.1.3, Ethernet0/1
R4#
测试实验结果
1.VPC1与VPC2互通是正常的
2.R1出现故障
由于模拟器的原因，R1关闭端口但与R2和R3连接的对应端口还是up，R1也无法关闭，所以将R2和R3对应的端口关闭掉。
R2：
R3：
显示R2和R3的静态路由切换到下面R4。
突然发现一个问题：R2的 e0/0 地址配置错了，赶紧更正。
数据通信路由走的备份路由。
3.R1恢复之后
将之前R1关闭的端口，R2和R3关闭的端口都放开。
R2路由自动切换到主路由
R3自动切换到主路由
通过浮动静态路由的实验，可以通过该特性，合理的使用，以增加网络的冗余和稳定性！
关于PNETLAB的Bug：
R1关机状态，但R2和R3对应的端口还是up，有知道如何解决的朋友，麻烦说下！
