Honghuang, I am engaged in science and technology in the Wuzu

After Mo left, Fang Hao began to think about the design of the network layer, which is designed based on the data link layer.

On the earth, the design of the network layer is designed by the people of country M, during the Cold War, the Soviet Union launched the first artificial earth satellite of mankind, and country M established the Advanced Research Projects Agency to develop the key technology of network communication – address resolution protocol ARP, which is the origin of the network layer.

Later, with the development of network technology, the network layer gradually included five protocols, ARP protocol, Internet control message protocol ICMP, virtual private network VPN, network address translation NAT, Internet routing protocol RIP, OSPF, BGP.

As can be seen from the name, the network layer is a technology related to IP addresses, which intelligently performs address translation according to the condition of the network.

The ARP protocol is used to find the host, the computer sends a message, sends a request containing the destination IP address to all hosts on the network, and receives all the messages returned by the workhorse, if the host meets the requirements, the calculation connects the host and subsequently communicates.

The ICMP protocol is used for auxiliary communication, describing the state of communication when transmitting information, such as datagram error information, network condition information, host status information, etc., these control messages are located in the transmitted data in the data link layer, used to determine whether the host is active, for inactive hosts, there is no need to send datagrams to it, because this is futile.

VPN protocol through a public network to establish a temporary, secure connection, mainly used in the internal network of the enterprise, the biggest feature is that digital encryption can be carried out, most of the smuggling software on the network uses this protocol, it can be seen that the network layer is the strengthening of the function of the data link layer.

The network address translation NAT protocol allows many computers to share an IP address to access the Internet, which can effectively solve the problem of insufficient public network addresses.

Internet routing protocol, play the function of information channel control, if an organization has a lot of computers, through this protocol to determine which computer has the permission to connect to the external network, such as which computers can connect to the internal network to receive mail, which computers can connect to the external network.

In summary, the network layer is a function to control the connection of the computer, and the reasonable design of the network layer can improve network efficiency, and users can control the network.

“It’s so hard! The network layer is completely a large piece of software that plays the function of connecting the network. Fang Hao stopped the pen in his hand, and looked at the sketch in his pen with a daze, each of these agreements can not be completed at this stage, but requires the development of software technology to mature.

The fourth layer of transport layer is the same, the transport layer is to control data to achieve two computers for data transmission, can also control multiple computers for data transmission at the same time, such as a hundred computers download a file at the same time, that is, create multiple logical connections on a network connection.

The transport layer has a buffering effect, when the network layer service quality can not meet the requirements, it will have been downloaded the computer as a host, so that there are multiple hosts to provide network services, so as to improve the quality of network service, to when the network layer service quality is better, it only uses very few network resources to complete the task, it can be seen that the transport layer is also a relatively intelligent software.

The fifth layer of the conversation layer, mainly for the two computers to carry out real-time dialogue, such as in the audio and video communication or download to get the effect of synchronization, can make the communication session in the communication failure, continue to resume communication, such as some files dozens of G, you can download for several days are no problem, if there is no session layer, once the link is broken, you need to download again.

The sixth layer is the presentation layer, one of the main functions is to provide a common language for communication, so that it can be interoperable, such as encoding conversion, Chinese-English conversion, communication at different terminals, such as people holding mobile phones and people using computers to communicate on the Internet.

The seventh layer is called the application layer, which can realize the communication of multiple system application processes, such as file transfer, access management, job transmission, banking transactions, order entry, etc., and different applications on the same computer can communicate with each other at the same time.

It can be seen that the physical layer, data link layer, and network layer are all related to hardware and implemented by hardware, while the transport layer, session layer, and application layer are all implemented by software.

If you want network technology to develop in the way of the earth, then it will take at least fifty or sixty years to develop to the level of the earth’s network, and Fang Hao thought of this and decided to make the network technology develop faster.

It decided to write a paper on network technology, called “Future Network Technology Conjecture”, to discuss how to develop a super network of all things.

“The web of the future, interesting, and written by a prophet.” In a secluded place in Redstone City, River held a magazine and saw this article.

“Everything is connected, real-time communication, can this really be achieved?” River thought to his heart.

Not only the river, countless people in Redstone City were attracted by Fang Hao’s future vision, and in this era of roaring when going out, it was difficult to imagine holding a computer with very little physical strength and communicating with friends thousands of miles away.

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“Hiroshi, is this what you said true? Is it really possible to connect everything? Ice asked.

For this paper, the Ice Banshee specially ran over to discuss the Internet with Fang Hao.

She was still confused about how Redstone would develop, but writing a paper that gave a bright light to computer research that was stuck almost in place, that is, to build network communications.

“Naturally, it is true, but the current scientific and technological strength is not enough, and it may take decades to develop.” Fang Hao explained.

“Can you tell me something specific? Your thesis is not deep enough, I want to know it specifically. The Ice Banshee said.

“What’s wrong? What do you want to know? Fang Hao asked.

“I want to know the data link layer you designed, and your drawings have been sent, but the institute has fallen into a bottleneck, it is difficult to meet the conditions you require, and I want to come and listen to your opinion.” The Ice Banshee said.

“Regarding the network, I only have some conjectures, and I also design some communication models through logic, and it takes a lot of effort to really realize it.” Fang Hao said.

“Heehee, I thought you would make a great discovery, but I didn’t expect it to stump you too.” The ice banshee was stunned, and then said.

Fang Hao smiled bitterly, science and technology have developed to the Internet age, and his knowledge in his previous life is no longer an advantage, because there are many modern social disciplines, and the classification is very complicated, Fang Hao naturally has not read monographs on network issues.

Network problems cannot be solved by a few people, and countless people must work together to climb this mountain.

“The question you asked before was simple, so I could find the answer to the problem, and now I haven’t encountered the problem you said.” Fang Hao said helplessly.