IPv4 over IPv6隧道：
在IPv4 Internet向IPv6 Internet过渡后期，IPv6网络被大量部署后，而IPv4网络只是散布在世界各地的一些孤岛。利用隧道技术可以在IPv6网络上创建隧道，从而实现IPv4孤岛的互联，IPv4孤岛能通过IPv6公网访问其他IPv4网络。
IPv4 over IPv6拓扑结构：
两个IPv4网络分别通过R1和R5与IPv6网络连接。IPv6网络的边界设备R2和R4支持IPv4和IPv6双协议栈。客户在R2和R4之间配置IPv4 over IPv6隧道，使物理分离的这两个IPv4网络可以互通
拓扑图
IPv4 over IPv6配置方法：
1、在两端IPv6网络边界路由器上配置IPv4-over-IPv6隧道
2、采用动态路由协议配置经过该隧道接口转发的路由
IPv4 over IPv6配置步骤：
1、配置IPv6网络的IPv6地址和IS-IS的IPv6特性，实现IPv6网络的IP连通性
[Huawei]sysname R2
[R2]ipv6
[R2]int g0/0/1
[R2-GigabitEthernet0/0/1]ipv6 enable
[R2-GigabitEthernet0/0/1]ipv6 address 2001::1 64
[R2]isis
[R2-isis-1]network-entity 10.0000.0000.0001.00
[R2-isis-1]ipv6 enable topology standard
[R2]int g0/0/1
[R2-GigabitEthernet0/0/1]isis ipv6 enable 1
[Huawei]sysname R3
[R3]ipv6
[R3]int g0/0/0
[R3-GigabitEthernet0/0/0]ipv6 enable
[R3-GigabitEthernet0/0/0]ipv6 address 2001::2 64
[R3]int g0/0/1
[R3-GigabitEthernet0/0/1]ipv6 enable
[R3-GigabitEthernet0/0/1]ipv6 address 2002::1 64
[R3]isis
[R3-isis-1]network-entity 10.0000.0000.0002.00
[R3-isis-1]ipv6 enable topology standard
[R3]int g0/0/0
[R3-GigabitEthernet0/0/0]isis ipv6 enable 1
[R3]int g0/0/1
[R3-GigabitEthernet0/0/1]isis ipv6 enable 1
[Huawei]sysname R4
[R4]ipv6
[R4]int g0/0/0
[R4-GigabitEthernet0/0/0]ipv6 enable
[R4-GigabitEthernet0/0/0]ipv6 address 2002::2 64
[R4]isis
[R4-isis-1]network-entity 10.0000.0000.0003.00
[R4-isis-1]ipv6 enable topology standard
[R4-isis-1]q
[R4]int g0/0/0
[R4-GigabitEthernet0/0/0]isis ipv6 enable 1
2、配置IPv4网络的IPv4地址和OSPF，实现IPv4网络的IP连通性
[Huawei]sysname R1
[R1]int g0/0/0
[R1-GigabitEthernet0/0/0]ip add 10.1.12.1 24
[R1]ospf
[R1-ospf-1]area 0
[R1-ospf-1-area-0.0.0.0]network 10.1.12.1 0.0.0.0
[R2]int g0/0/0
[R2-GigabitEthernet0/0/0]ip add 10.1.12.2 24
[R2]ospf
[R2-ospf-1]area 0
[R2-ospf-1-area-0.0.0.0]network 10.1.12.2 0.0.0.0
[R4]int g0/0/1
[R4-GigabitEthernet0/0/1]ip add 10.1.45.4 24
[R4]ospf
[R4-ospf-1]area 0
[R4-ospf-1-area-0.0.0.0]network 10.1.45.4 0.0.0.0
[Huawei]sysname R5
[R5]int g0/0/0
[R5-GigabitEthernet0/0/0]ip add 10.1.45.5 24
[R5]ospf
[R5-ospf-1]area 0
[R5-ospf-1-area-0.0.0.0]network 10.1.45.5 0.0.0.0
3、配置tunnel接口
配置R2tunnel接口
[R2]interface Tunnel 0/0/1
[R2-Tunnel0/0/1]tunnel-protocol ipv4-ipv6
[R2-Tunnel0/0/1]ip add 10.1.24.2 24
[R2-Tunnel0/0/1]source g0/0/1
[R2-Tunnel0/0/1]destination 2002::2
配置R4tunnel接口
[R4]int Tunnel 0/0/1
[R4-Tunnel0/0/1]tunnel-protocol ipv4-ipv6
[R4-Tunnel0/0/1]ip add 10.1.24.4 24
[R4-Tunnel0/0/1]source g0/0/0
[R4-Tunnel0/0/1]destination 2001::1
配置隧道接口路由
[R2]ospf
[R2-ospf-1]area 0
[R2-ospf-1-area-0.0.0.0]network 10.1.24.2 0.0.0.0
[R4]ospf
[R4-ospf-1]area 0
[R4-ospf-1-area-0.0.0.0]network 10.1.24.4 0.0.0.0
4、测试连通性
在R2上查看学到的路由
[R2]dis ip routing-table protocol ospf
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Public routing table : OSPF
Destinations : 1 Routes : 1
OSPF routing table status : <Active>
Destinations : 1 Routes : 1
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.1.45.0/24 OSPF 10 1563 D 10.1.24.4 Tunnel0/0/1
OSPF routing table status : <Inactive>
Destinations : 0 Routes : 0
在R1上pingR5测试
<R1>ping 10.1.45.5
PING 10.1.45.5: 56 data bytes, press CTRL_C to break
Reply from 10.1.45.5: bytes=56 Sequence=1 ttl=253 time=60 ms
Reply from 10.1.45.5: bytes=56 Sequence=2 ttl=253 time=50 ms
Reply from 10.1.45.5: bytes=56 Sequence=3 ttl=253 time=30 ms
Reply from 10.1.45.5: bytes=56 Sequence=4 ttl=253 time=30 ms
Reply from 10.1.45.5: bytes=56 Sequence=5 ttl=253 time=40 ms
