How to demonstrate IPv6 protocol compatibility

Networks are more complex and changeable than we think, and IPv4 network protocols have become deep-rooted. However, when it is huge, it may also be exhausted. Therefore, IPv6 must be used, but it is not yet popular. However, we need to know about IPv6.

By that time, the upgrade system will need to maintain interoperability with the IPv4 system. Over time, the burden of interoperability will be borne by early implementers and transferred to the maintenance personnel of traditional systems. In any case, systems that support both IPv4 and IPv6 protocols are necessary ｡

Dual-stack nodes are not a new concept. For example, many corporate hosts support both Internet connectivity and early versions of NovellNetware (in Netware5, IP addresses have replaced ip x as network-layer protocols). These Hosts already support two fundamentally different network stacks. The connection capabilities to the Internet are provided through the TCP/IP protocol stack, the connection capability to Netware is provided through the IPX stack. The link layer receives data segments and disconnects them. The segment header specifies whether the datagram is sent to the TCP/IP stack or to the IPX stack, then pass the package to the correct stack for processing ｡

Dual-stack Node

IPv4/IPv6 Dual-stack nodes work in the same way as other types of multi-stack nodes. The link layer receives data segments, disconnects them, and checks the headers. If the first field in the IPv4/IPv6 Header is, that is, if the version number of the IP package is 4, the packet is processed by the IPv4 stack. if the version number is 6, the IPv6 stack processes the packet ｡

The simplest double stack operation is to support only IPv4 and IPv6, but not tunnel. For most nodes, especially if the Internet application software of these nodes has been upgraded to support both IPv4 and IPv6, this function is sufficient. Therefore, it is similar to accessing IPv4 network services, the same application can also be used to access local IPv6 network services. nodes can interoperate with any IPv4 or IPv6 node, but only the network with the connection capability is limited. In the example of Figure 12-3, nodes that can interoperate with dual-stack node D include IPv4 nodes in Network A and Network B, IPv6 nodes, and all IPv4 nodes in network M, however, D cannot interwork with nodes in Network C. Network C is A strict IPv6 network, and there is no IPv6 path between network A and Network C. Routers connected to Network A and network M only support IPv4, therefore, IPv6 packets cannot be forwarded to Network C through network M ｡

Tunnel-mode Dual-stack nodes increase the ability to perform interoperability on IPv4 networks, instead of an IPv6 router, the IPv6 packet is transmitted in the IPv4 network as a tunnel to change the sample in Figure 12-3. For example, if node D can transmit an IPv6 packet in IPv4 as a tunnel, the local IPv4 router can forward packets to Network C. If the node supports automatic tunneling at the same time, seamless operations can be performed; otherwise, some link configurations are required ｡