Cisco设备关于GRE的小案例
实验拓扑：
实验设备：
五台cisco路由器
有三台分别作r1、r2、r3
另两台作pc1、pc2
实验步骤：
为每个设备的各个端口配置正确的ip
在r1和r2上配置一条通往公共网的默认路由、创建gre隧道、配置通过隧道的路由
测试连通性
实验目的：
能使1.0网段的主机能通过gre隧道和2.0网段的主机通讯
参考配置：
r1#show ip route
Codes: 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
Gateway of last resort is 61.130.130.2 to network 0.0.0.0
C 192.168.4.0/24 is directly connected, Tunnel10
C 192.168.1.0/24 is directly connected, Serial1/1
S 192.168.2.0/24 is directly connected, Tunnel10
61.0.0.0/30 is subnetted, 1 subnets
C 61.130.130.0 is directly connected, Serial1/0
S* 0.0.0.0/0 [1/0] via 61.130.130.2
r1#show running-config
Building configuration...
Current configuration : 1003 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname r1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
!
!
ip cef
!
!
interface Tunnel10
ip address 192.168.4.1 255.255.255.0
tunnel source 61.130.130.1
tunnel destination 61.130.132.1
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface Serial1/0
ip address 61.130.130.1 255.255.255.252
serial restart-delay 0
!
interface Serial1/1
ip address 192.168.1.254 255.255.255.0
serial restart-delay 0
!
interface Serial1/2
no ip address
shutdown
serial restart-delay 0
!
interface Serial1/3
no ip address
shutdown
serial restart-delay 0
!
ip http server
ip route 0.0.0.0 0.0.0.0 61.130.130.2
ip route 192.168.2.0 255.255.255.0 Tunnel10
!
!
control-plane
!
!
line con 0
line aux 0
line vty 0 4
!
!
end
r2#show running-config
Building configuration...
Current configuration : 757 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname r2
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
!
!
ip cef
!
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface Serial1/0
ip address 61.130.130.2 255.255.255.252
serial restart-delay 0
!
interface Serial1/1
ip address 61.130.132.2 255.255.255.252
serial restart-delay 0
!
interface Serial1/2
no ip address
shutdown
serial restart-delay 0
!
interface Serial1/3
no ip address
shutdown
serial restart-delay 0
!
ip http server
!
!
control-plane
!
!
line con 0
line aux 0
line vty 0 4
!
!
end
r3#show ip route
Codes: 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
Gateway of last resort is 61.130.132.2 to network 0.0.0.0
C 192.168.4.0/24 is directly connected, Tunnel20
S 192.168.1.0/24 is directly connected, Tunnel20
C 192.168.2.0/24 is directly connected, Serial1/0
61.0.0.0/30 is subnetted, 1 subnets
C 61.130.132.0 is directly connected, Serial1/1
S* 0.0.0.0/0 [1/0] via 61.130.132.2
r3#show running-config
Building configuration...
Current configuration : 1018 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname r3
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
!
!
ip cef
!
!
interface Tunnel20
ip address 192.168.4.2 255.255.255.0
tunnel source 61.130.132.1
tunnel destination 61.130.130.1
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface Serial1/0
ip address 192.168.2.254 255.255.255.0
serial restart-delay 0
!
interface Serial1/1
ip address 61.130.132.1 255.255.255.252
serial restart-delay 0
!
interface Serial1/2
no ip address
shutdown
serial restart-delay 0
!
interface Serial1/3
no ip address
shutdown
serial restart-delay 0
!
ip http server
ip route 0.0.0.0 0.0.0.0 61.130.132.2
ip route 192.168.1.0 255.255.255.0 Tunnel20
!
!
control-plane
!
!
line con 0
line aux 0
line vty 0 4
!
!
End
测试：
Pc1ping pc2
pc1#ping 192.168.2.100
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 136/148/172 ms
Pc2pingpc1
pc2#ping 192.168.1.100
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 100/147/204 ms
跟踪一下路由：
pc1#traceroute ip
Target IP address: 192.168.2.100
Source address: 192.168.1.100
Numeric display [n]:
Timeout in seconds [3]:
Probe count [3]:
Minimum Time to Live [1]:
Maximum Time to Live [30]:
Port Number [33434]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Type escape sequence to abort.
Tracing the route to 192.168.2.1
1 192.168.1.254 68 msec 36 msec 52 msec
2 192.168.4.2 100 msec 136 msec 140 msec
3 192.168.2.100 188 msec 228 msec *
很显然ping包是从虚拟的隧道通过的