第一步：配置R1
interface Loopback0
ip address 1.1.1.1 255.255.255.0
!
interface Tunnel1
ip address 10.0.0.1 255.255.255.0
tunnel source FastEthernet0/0
tunnel destination 23.0.0.3
!
interface FastEthernet0/0
ip address 12.0.0.1 255.255.255.0
!
router eigrp 1
network 12.0.0.0
no auto-summary
!
router eigrp 11
network 1.0.0.0
network 10.0.0.0
no auto-summary
//这里启用了2个eigrp进程，在第一个进程里没可以全部通告（直接通告直连的路由），不然1.1.1.1 去3.3.3.3走物理接口，而不是tunnel，
R3上同理
第二步：配置R2
interface Loopback0
ip address 2.2.2.2 255.255.255.0
!
interface FastEthernet0/0
ip address 12.0.0.2 255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 23.0.0.2 255.255.255.0
!
router eigrp 1
network 12.0.0.0
network 23.0.0.0
no auto-summary
第三步：配置R3
interface Loopback0
ip address 3.3.3.3 255.255.255.0
!
interface Tunnel1
ip address 10.0.0.2 255.255.255.0
tunnel source FastEthernet0/1
tunnel destination 12.0.0.1
!
interface FastEthernet0/1
ip address 23.0.0.3 255.255.255.0
duplex auto
speed auto
!
router eigrp 1
network 23.0.0.0
no auto-summary
!
router eigrp 11
network 3.0.0.0
network 10.0.0.0
no auto-summary
May 13 15:18:07.431: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel1, changed state to up
May 13 15:18:07.459: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 11: Neighbor 10.0.0.2 (Tunnel1) is up: new adjacency
//从上面两句消息中，我们可以看到tunnel up了
第四步：测试，我们只在R1上进行测试
R1# sh 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 not set
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
3.0.0.0/24 is subnetted, 1 subnets
D 3.3.3.0 [90/297372416] via 10.0.0.2, 00:21:00, Tunnel1 //下一跳去10.0.0.2
23.0.0.0/24 is subnetted, 1 subnets
D 23.0.0.0 [90/30720] via 12.0.0.2, 00:29:41, FastEthernet0/0
10.0.0.0/24 is subnetted, 1 subnets
C 10.0.0.0 is directly connected, Tunnel1
12.0.0.0/24 is subnetted, 1 subnets
C 12.0.0.0 is directly connected, FastEthernet0/0
R1#traceroute 3.3.3.3 so 1.1.1.1
Type escape sequence to abort.
Tracing the route to 3.3.3.3
1 10.0.0.2 104 msec * 84 msec
//这里我们可以看到从隧道里通过