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The birth of IPV4 - Big bug!
The birth of IPV4 originated from the birth of the Internet, and the birth of the Internet, the main function is the golden bell in the United States in the 1960s to deal with military external troubles.
In the 1960s and 1970s, the United States was particularly affected by foreigners, the Cuban nuclear bomb crisis, the military competition with the former Soviet Union, and the Vietnam War. The modern battles seized the opportunity and the communication path could not be cut off. In the 1960s, the connection methods of the four major military computers in the United States were centrally controlled. However, when the central control system was attacked, the rest of the military computers would be paralyzed!
To overcome this problem, to ensure that the central control system is still attacked by the military, the rest of the computer can still operate normally, and the APA network (the predecessor of the Internet) was proposed. This network communication method does not transfer the data to the destination as easily as the central control type but transmits the data between the different sites of the network like a relay race by means of "packet exchange". In this case, even if the central system is attacked, the remaining military computers can seek a new communication center for information exchange because they have site interconnections with each other.
APA.com initially had only 4 computers connected, but by 1970, there were 110 computers connected to the APA network. The problem arises - how to connect different types of computers in the same way and with common standards. To ensure mutual sharing between them?
So, the "Network Control Protocol" (TCP/IP protocol) was born, that is, IPV4 was born. It promoted the intercommunication of the world network as a communication standard, but at the same time "Big bug" was also born - when the United States created the Internet, it intended to use In military use, after seriously considering the total population of the United States and the number of computers at that time, I felt that the 32nd power of 2, that is, more than 4 billion IP addresses, is enough for the United States to go global, but they underestimated the Internet bursting spread. Speed, a network and an IP address, the Internet outbreak has directly exhausted IP addresses for decades, which has become the biggest dilemma restricting the development of the Internet.
IPV4 VS IPV6
The IP address is exhausted, and naturally, we must find a solution. Therefore, the IPV6 protocol is born out of the original intention of saving the Internet. Under the IPV6 protocol, the address is 128 bits, and the total number of addresses is 340 trillion megabytes. Every grain of sand on the earth can have an IP address.
IPV4 PK IPV6, first of all, IPV6 wins over the total number of addresses. Secondly, from the perspective of security features, IPV4 is not encrypted, and security risks are large, while the IPV6 encryption, addresses are not easily attacked and traced, and security risks are small. Finally, the IPV4 address is exhausted. In order to solve this problem, NAT technology has emerged. The router broadcast operation directly reduces the network propagation speed, while the IPV6 address is sufficient, and NAT is not needed so that the propagation speed is faster, and the quality is better.
But unfortunately, even though IPV6 has been proposed for many years, even if it has many benefits, its penetration rate in China is only 0.39%, still less than 1%. Why is IPV6 replacing IPV4? Why is it so difficult?
The invention of NAT technology has no power to promote IPV6
China's Internet started late, so it is too late to understand that the IPV4 address is not enough. But this does not prevent China's warriors from overtaking and dare to innovate - we use NAT technology to create the world's largest private network.
The private network corresponds to the concept of the public network. Using the mailing system as a metaphor, suppose you have a public IP, which is equivalent to having a specific address in the virtual world. In this situation, you can give this address to people, and others can give you your address. Send a message.
But the private network is different, just like if you live in a compound, you don't have a specific address, so all your incoming and outgoing emails must be conveyed by the address-based communication room. In this situation, if there is an email, you need by your own signature, the grandfather of the communication room will say: Sorry, he has no right to sign, all the mail has to be transferred by me. So, the post office staff had to give up.
The IP address is limited. The private network (the network of the IP address group) cannot contact the public IP address, so the transparent gateway is used to transit. This is the NAT technology.
The birth of NAT technology temporarily solved the problem of missing IP addresses, but it also became the power to block the promotion of IPV6. Under the problem that existing NAT technology can solve IPV4, people have no incentive to promote IPV6.
The transition from IPV4 to IPV6 is not easy
At this stage, the IP network is still dominated by IPV4. The IPV6 network is deployed and used only in a small area (for example, the local campus network, the school will not tell you), the transition from IPV4 to IPV6 can hardly be achieved in one go, and the transition is slow. On the selection, IPV4 and IPV6 coexistence strategies and transition technologies generally have three types, as follows:
1, double stack technology
Under dual-stack technology, the host or network device supports both IPV4 and IPV6 dual-stack protocols. It is easy to understand that the host and the network device have both the address under the IPV4 protocol and the address under the IPV6 protocol. For example, a router is a dual-stack device. By default, it can support IPV4 and can forward IPV4 packets. At the same time, if a unicast address of IPV6 is also assigned to the router, then the router will have IPV6 data forwarding capability. Under the dual stack technology, the IPV4 and IPV6 planks do not interfere with each other and work independently.
2. Tunnel technology
Tunnel technology is more difficult to solve the problem of IPV6 communication. Now the main body of IPV4 network technology is IPV4, and the fragmented IPV6 network has become a scattered information island. In the context of two IPV6 devices being placed in an IPV4 network, the interconnect relies on tunneling.
Under tunnel technology, R1 and R2 are dual-stack routers, and IPV4 and IPV6 are respectively identified by both ends of the dual-stack router. The existence of a single dual-stack router realizes the interconnection of IPV4 and IPV6, and the presence of two routers opens the interconnection tunnel of IPV6 to IPV6.
3, NAT64 technology
NAT64 technology is actually a translation technology that implements protocol conversion between IPV4 and IPV6, enabling flexible conversion of packets between V4 and V6 formats. When the nodes of the IPV4 network need to communicate directly with the nodes of the IPV6 network, it is of course not feasible by default because the two protocol stacks are not compatible. However, with one device, the protocol translation of IPV6 and IPV4 is realized by the device, and the above communication requirements can be realized.
The three conversion technologies have their own advantages, but each has its own flaws. Let's not say that the dual-stack technology requires IPV4 and IPV6 addresses one-to-one correspondence, and the application is troublesome. At the same time, it cannot achieve the interconnection between IPV6. Although the tunnel technology can realize the interconnection of IPV6, it has a great security risk, IPV6. Exposure to the public network, there is the possibility of being hijacked at any time, and the configuration and maintenance of the tunnel are also more troublesome.
The most difficult part is the application of NAT64 technology. At present, the entire Internet is built on the basis of IPV4. When IPV6 data is transmitted through 6to4 technology, the IPV6 device network needs to be switched from IPV4 network to IPV6 network, and then the other end of the IPV4 message is transmitted through the 4to6 technology. In this process, in the process of 4 network cut 6 network, local temporary network disconnection is necessary, and disconnection of the network is bound to bring many lives to people. inconvenient. In addition, under NAT64, the protocol conversion manually configures the static mapping relationship, so that the IPV4 network actively initiates the connection to access the IPV6 network, but the protocol conversion process is time-consuming and laborious, and the efficiency is low.
All of the above defects have become the obstacles that restrict the promotion of IPV6.
The promotion of IPV6 makes operators unprofitable
First of all, from the perspective of virtual networks, the IPV6 and IPV4 protocols are too different and incompatible. At the same time, they are divided into multiple layers on the Internet. Each layer has corresponding protocols and specifications, which are the only fine between layers. Waist, the replacement of the IP layer will affect many other layers. Therefore, from the perspective of network upgrade, the conversion of IPV4 to IPV6 is not easy.
