Features and applications between IPv4 routing technology and IPv6

With the development of China's routing technology, IPv4 routing technology is also widely used. Here we mainly introduce the characteristics and application between IPv4 routing technology and IPv6. As the Internet expands, the existing IPv4 addresses are in short supply. Although the technology of using addresses such as allocating temporary IPv4 addresses or translating network addresses into NAT addresses is used, to some extent, the IPv4 address is insufficient.

But it also increases the overhead of Address Resolution and processing, leading to failure of some high-level applications, and still cannot avoid the problem that IPv4 addresses will be allocated soon. The IPv6 protocol with a length of 128 B IP address is used to completely solve the problem of IPv4 address insufficiency. It also significantly improves the address capacity, security, network management, mobility, and service quality, it is one of the core standards used by the next generation Internet protocol. IPv6 is not compatible with IPv4 routing technology, but it is compatible with all other TCP/IP protocol families. That is, IPv6 can completely replace IPv4.

Before IPv6, therefore, the IPv4/IPv6 interconnection technology must be developed to ensure the smooth transition from IPv4 to IPv6. In addition, intercommunication technology should ensure efficient and seamless information transmission. IETF has set up a dedicated NGTRANS working group to conduct research on IPv4/IPv6 transition and efficient and seamless interconnection. A variety of transitional technologies and interconnection solutions have emerged. These technologies have their own characteristics and are used to solve communication problems in different transitional periods and environments. Some of them are already quite mature and have formed RFC, some still need to be improved as Internet draft.

Three basic technologies for intercommunication between IPv6 and IPv4

DualStack)

The dual-protocol stack technology is the most direct way to make IPv6 nodes compatible with IPv4 nodes. The application objects are communication nodes such as hosts and routers. The IPv6 protocol stack is used when IPv6 nodes and IPv6 nodes of the Two-protocol stack are interconnected, and the IPv4 protocol stack is used when IPv4 nodes are interconnected with each other by means of 4over6. When an IPv6 node accesses an IPv4 node, it first requests a temporary IPv4 address from the dual-stack server and obtains the TEPTunnelEndPoint of the Gateway Router from the dual-stack server. On this basis, IPv6 nodes form a 4 over 6 IP package. 4 over 6 packets are transmitted to the Gateway Router through the IPv6 network, and the Gateway Router Removes Its IPv6 Header, send an IPv4 packet to an IPv4 node through an IPv4 network. The Gateway Router must remember the ing between the IPv6 source address and the IPv4 temporary address so that the IP packet sent from the IPv4 node can be forwarded to the IPv6 node in the opposite direction. This method is fully compatible with IPv4 and IPv6. However, due to the need for dual-route infrastructure, the network complexity is increased and the problem of IP address depletion still cannot be solved.

Tunnel Technology)

Tunnel technology provides a method to transmit IPv6 data using the existing IPv4 routing technology system: the IPv6 package is encapsulated in an IPv4 packet as non-structural data, transmitted by IPv4 routing technology. Based on different establishment methods, tunnel technology can be divided into two types: manual configuration tunnel and automatic configuration tunnel. The tunnel technology cleverly utilizes the existing IPv4 routing technology. It provides a method to enable communication between IPv6 nodes during the transition period, however, it cannot solve the problem of intercommunication between IPv6 nodes and IPv4 nodes.

NAT-PT

NAT-PT is a pure IPv6 node and IPv4 node intercommunication mode, all the translation work including the address, protocol is done by the network device. The Gateway Router that supports the NAT-PT should have an IPv4 address pool for use during packet forwarding from IPv6. In addition, the Gateway Router supports DNS-ALG (DNS, Application Layer Gateway), play a role when IPv6 nodes access IPv4 nodes. In response to the preceding networking principles, we believe that phased evolution from IPv4 to IPv6 is the most feasible method. In summary, there are four phases:

In the first stage, there are more and more IPv6 "small islands" in IPv4 "ocean ". At this time, appropriate transition mechanisms are required. The available mechanisms include tunnel proxy, 6 over 4, 6 to 4, and NAT-PT.

In the second stage, more and more IPv6 "Small Island" gradually become larger and more, and become another "ocean" comparable to IPv4 "ocean". The NAT transition mechanism may be more efficient.

In the third stage, IPv6 becomes the mainstream in the network world, and IPv4 networks are fewer and fewer, forming the coexistence of IPv6 "ocean" and IPv4 "Island, possible Transition Mechanisms are NAT-PT and DSTM.

In the fourth stage, when IPv6 is successfully applied, it should be pure IPv6 "ocean" and IPv4 "island" will not exist. At this time, no transitional technology is required. Each network node adopts an IPv6-based communication mode.

The limitations of IPv4 are destined that the Internet supported by IPv4 routing technology will gradually and smoothly transition to the next-generation Internet with IPv6 as the core, different transitional technologies and mechanisms should be used in different transitional stages and different network environments. So far, there has not been a general standard transition mechanism. The existing transition mechanisms have their own advantages and disadvantages and their respective applicability. They only have to adapt to local conditions and perform scientific analysis, in different transition stages, the application type, scope, and system type can be clearly defined, and the conversion mechanism can be reasonably selected to achieve a smooth transition from an IPv4 routing technology network to an IPv6 network at a lower cost.