实验目的：
1.通过虚链路的方式使远离骨干区域的区域能够实现收敛
2.通过tunel0的方式进行解决
实验拓扑：
实验步骤：
方法一：通过虚链路解决
R1:
router ospf 1
router-id 1.1.1.1
log-adjacency-changes
network 1.1.1.1 0.0.0.0 area 0
network 10.1.1.1 0.0.0.0 area 0
R2:
router ospf 1
router-id 1.1.1.1
log-adjacency-changes
network 1.1.1.1 0.0.0.0 area 0
network 10.1.1.1 0.0.0.0 area 0
area 1 virtual-link 3.3.3.3
R3:
router ospf 1
log-adjacency-changes
network 3.3.3.3 0.0.0.0 area 1
network 10.1.2.2 0.0.0.0 area 1
network 10.1.3.1 0.0.0.0 area 2
area 1 virtual-link 2.2.2.2
方法二：通过tunnel 解决： 这种方法有点问题：
R1:
router ospf 1
router-id 1.1.1.1
log-adjacency-changes
network 1.1.1.1 0.0.0.0 area 0
network 10.1.1.1 0.0.0.0 area 0
network 192.168.1.0 0.0.0.255 area 2
interface Tunnel0 //tunnel0
ip address 192.168.1.1 255.255.255.0 //写IP地址
tunnel source 10.1.1.1 //出口IP地址
tunnel destination 10.1.2.2 //R3相连的IP地址即建立连接的IP地址
R1#SHOW Ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
2.2.2.2 1 FULL/ - 00:00:39 10.1.1.2 Serial1/1
3.3.3.3 1 FULL/ - 00:00:33 192.168.1.3 Tunnel0
R1#show ip ospf neighbor detail
Neighbor 2.2.2.2, interface address 10.1.1.2
In the area 0 via interface Serial1/1
Neighbor priority is 1, State is FULL, 6 state changes
DR is 0.0.0.0 BDR is 0.0.0.0
Options is 0x42
Dead timer due in 00:00:33
Neighbor is up for 00:54:37
Index 1/1, retransmission queue length 0, number of retransmission 1
First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
Last retransmission scan length is 1, maximum is 1
Last retransmission scan time is 0 msec, maximum is 0 msec
Neighbor 3.3.3.3, interface address 192.168.1.3
In the area 2 via interface Tunnel0
Neighbor priority is 1, State is FULL, 6 state changes
DR is 0.0.0.0 BDR is 0.0.0.0
Options is 0x42
Dead timer due in 00:00:38
Neighbor is up for 00:21:04
Index 1/2, retransmission queue length 0, number of retransmission 1
First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
Last retransmission scan length is 1, maximum is 1
Last retransmission scan time is 0 msec, maximum is 0 msec
R1#
R1#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
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
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/65] via 10.1.1.2, 00:17:09, Serial1/1
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/129] via 10.1.1.2, 00:16:44, Serial1/1
4.0.0.0/32 is subnetted, 1 subnets
O 4.4.4.4 [110/11176] via 192.168.1.3, 00:16:44, Tunnel0
10.0.0.0/24 is subnetted, 3 subnets
O 10.1.3.0 [110/11175] via 192.168.1.3, 00:16:44, Tunnel0
O IA 10.1.2.0 [110/128] via 10.1.1.2, 00:16:44, Serial1/1
C 10.1.1.0 is directly connected, Serial1/1
C 192.168.1.0/24 is directly connected, Tunnel0
R1#show ip ospf int tunnel 0
Tunnel0 is up, line protocol is up
Internet Address 192.168.1.1/24, Area 2
Process ID 1, Router ID 1.1.1.1, Network Type POINT_TO_POINT, Cost: 11111
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:00
Index 1/3, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 3.3.3.3
Suppress hello for 0 neighbor(s)
R3:
router ospf 1
log-adjacency-changes
network 3.3.3.3 0.0.0.0 area 1
network 10.1.2.2 0.0.0.0 area 1
network 10.1.3.1 0.0.0.0 area 2
network 192.168.1.0 0.0.0.255 area 2
interface Tunnel0
ip address 192.168.1.3 255.255.255.0
tunnel source 10.1.2.2
tunnel destination 10.1.1.1
R3#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
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
1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/129] via 10.1.2.1, 00:18:03, Serial1/0
2.0.0.0/32 is subnetted, 1 subnets
O IA 2.2.2.2 [110/65] via 10.1.2.1, 00:18:03, Serial1/0
3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback0
4.0.0.0/32 is subnetted, 1 subnets
O 4.4.4.4 [110/65] via 10.1.3.2, 00:18:03, Serial1/1
10.0.0.0/24 is subnetted, 3 subnets
C 10.1.3.0 is directly connected, Serial1/1
C 10.1.2.0 is directly connected, Serial1/0
O IA 10.1.1.0 [110/128] via 10.1.2.1, 00:18:03, Serial1/0
C 192.168.1.0/24 is directly connected, Tunnel0
R3#show ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
2.2.2.2 1 FULL/ - 00:00:36 10.1.2.1 Serial1/0
1.1.1.1 1 FULL/ - 00:00:31 192.168.1.1 Tunnel0
4.4.4.4 1 FULL/ - 00:00:30 10.1.3.2 Serial1/1
R1#show ip ospf int tunnel 0
Tunnel0 is up, line protocol is up
Internet Address 192.168.1.1/24, Area 2
Process ID 1, Router ID 1.1.1.1, Network Type POINT_TO_POINT, Cost: 11111
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:08
Index 1/3, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 3.3.3.3
Suppress hello for 0 neighbor(s)
实验心得：
在一个ospf自治系统中，如果一个区域与area 0脱离也就是说不与骨干区域相连的话，一般可以通过虚链路的方式解决，但是
可以通过tunnel 的方式解决，类似与×××的隧道技术。
在R2和R3上做：正确的方法是在R2,R3上做。
R1:
R1#SHOW IP ROUTE
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
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
2.0.0.0/32 is subnetted, 1 subnets
O IA 2.2.2.2 [110/65] via 10.1.1.2, 00:05:38, Serial1/1
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/129] via 10.1.1.2, 00:05:38, Serial1/1
4.0.0.0/32 is subnetted, 1 subnets
O IA 4.4.4.4 [110/11240] via 10.1.1.2, 00:05:38, Serial1/1
10.0.0.0/24 is subnetted, 3 subnets
O IA 10.1.3.0 [110/11239] via 10.1.1.2, 00:05:38, Serial1/1
O IA 10.1.2.0 [110/128] via 10.1.1.2, 00:05:38, Serial1/1
C 10.1.1.0 is directly connected, Serial1/1
O 192.168.1.0/24 [110/11175] via 10.1.1.2, 00:05:38, Serial1/1
R2:
interface Tunnel0
ip address 192.168.1.1 255.255.255.0
tunnel source 10.1.2.1
tunnel destination 10.1.2.2
router ospf 1
log-adjacency-changes
network 2.2.2.2 0.0.0.0 area 1
network 10.1.1.2 0.0.0.0 area 0
network 10.1.2.1 0.0.0.0 area 1
network 192.168.1.1 0.0.0.0 area 0
R2# show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
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
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/65] via 10.1.1.1, 00:04:30, Serial1/0
2.0.0.0/24 is subnetted, 1 subnets
C 2.2.2.0 is directly connected, Loopback0
3.0.0.0/32 is subnetted, 1 subnets
O 3.3.3.3 [110/65] via 10.1.2.2, 00:07:49, Serial1/1
4.0.0.0/32 is subnetted, 1 subnets
O IA 4.4.4.4 [110/11176] via 192.168.1.2, 00:04:30, Tunnel0
10.0.0.0/24 is subnetted, 3 subnets
O IA 10.1.3.0 [110/11175] via 192.168.1.2, 00:04:30, Tunnel0
C 10.1.2.0 is directly connected, Serial1/1
C 10.1.1.0 is directly connected, Serial1/0
C 192.168.1.0/24 is directly connected, Tunnel0
R3：
interface Tunnel0
ip address 192.168.1.2 255.255.255.0
tunnel source 10.1.2.2
tunnel destination 10.1.2.1
router ospf 1
log-adjacency-changes
network 3.3.3.3 0.0.0.0 area 1
network 10.1.2.2 0.0.0.0 area 1
network 10.1.3.1 0.0.0.0 area 2
network 192.168.1.2 0.0.0.0 area 0
R3# show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
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
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/11176] via 192.168.1.1, 00:05:16, Tunnel0
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/65] via 10.1.2.1, 00:08:31, Serial1/0
3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback0
4.0.0.0/32 is subnetted, 1 subnets
O 4.4.4.4 [110/65] via 10.1.3.2, 00:08:31, Serial1/1
10.0.0.0/24 is subnetted, 3 subnets
C 10.1.3.0 is directly connected, Serial1/1
C 10.1.2.0 is directly connected, Serial1/0
O 10.1.1.0 [110/11175] via 192.168.1.1, 00:05:16, Tunnel0
C 192.168.1.0/24 is directly connected, Tunnel0
第三种方法：通过ospf的不同进程的重分布来建立：
在R3上的配置：
router ospf 1
router-id 3.3.3.3
log-adjacency-changes
redistribute ospf 2 subnets 将ospf的进程2重分布进ospf进程1，
network 10.1.2.0 0.0.0.255 area 1
network 33.33.33.0 0.0.0.255 area 1
!
router ospf 2 这里又起了一个ospf的进程，这个进程会和R4的ospf进程建立邻居。
log-adjacency-changes
redistribute ospf 1 subnets 然后将ospf进程1充分布到进程2，这样路由通过进程1学到了，同时路由也得到了同步。
network 10.1.3.1 0.0.0.0 area 2
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 not set
33.0.0.0/24 is subnetted, 1 subnets
C 33.33.33.0 is directly connected, Loopback0
4.0.0.0/32 is subnetted, 1 subnets
O 4.4.4.4 [110/65] via 10.1.3.2, 00:00:08, Serial1/1
22.0.0.0/32 is subnetted, 1 subnets
O IA 22.22.22.22 [110/65] via 10.1.2.1, 00:08:47, Serial1/0
10.0.0.0/24 is subnetted, 3 subnets
C 10.1.3.0 is directly connected, Serial1/1
C 10.1.2.0 is directly connected, Serial1/0
O IA 10.1.1.0 [110/128] via 10.1.2.1, 00:08:47, Serial1/0
11.0.0.0/32 is subnetted, 1 subnets
O IA 11.11.11.11 [110/129] via 10.1.2.1, 00:08:47, Serial1/0
在R4上的配置：
R4#show run | b r o
router ospf 1
log-adjacency-changes
network 4.4.4.4 0.0.0.0 area 2
network 10.1.3.2 0.0.0.0 area 2
R4# 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 not set
33.0.0.0/24 is subnetted, 1 subnets
O E2 33.33.33.0 [110/1] via 10.1.3.1, 00:03:46, Serial1/0
4.0.0.0/24 is subnetted, 1 subnets
C 4.4.4.0 is directly connected, Loopback4
22.0.0.0/32 is subnetted, 1 subnets
O E2 22.22.22.22 [110/65] via 10.1.3.1, 00:03:46, Serial1/0
10.0.0.0/24 is subnetted, 3 subnets
C 10.1.3.0 is directly connected, Serial1/0
O E2 10.1.2.0 [110/64] via 10.1.3.1, 00:03:46, Serial1/0
O E2 10.1.1.0 [110/128] via 10.1.3.1, 00:03:46, Serial1/0
11.0.0.0/32 is subnetted, 1 subnets
O E2 11.11.11.11 [110/129] via 10.1.3.1, 00:03:46, Serial1/0
这样问题得到解决.