Suppose Xiao Ming needs to pass a movie to Xiao Hua. This movie has 1G. Obviously, it is impossible to transfer 1G of content to Xiaohua at a time, because neither the network card nor their respective computers can process such a large amount of content at a time, but can only be cut into 10 or more, so that Xiaoming’s machine and Xiaohua’s machine can bear the traffic. Then there is a layer of specialized data is divided into a piece of transmission, and to each piece of data with a serial number, so that the packet sent to the receiving entity is also received in order, this layer is the transport layer (TCP layer). After splitting into packets, you must add a header to each packet, so that each packet knows the address of the flower. So this is the IP layer, and the IP layer is also responsible for finding the most appropriate path. The packet is divided at the IP layer and then transmitted by the network adapter. The network adapter then adds some headers and tails (such as destination MAC addresses and source MAC addresses) to the packet after cutting the transport layer. And find the address of the next machine according to the IP (ARP (Address resolution protocol) : the MAC address is obtained from the local ARP cache table; The MAC address in the ARP cache table is obtained from ARP broadcast. If the MAC address of the destination host is not obtained, the packet is broadcast to the switch. The switch broadcasts the packet to obtain the MAC address for the next transmission. If the destination host is not on the local network, encapsulate the destination MAC address of the link layer protocol into the gateway MAC address and submit it to the gateway device for processing. After arriving at floret’s computer, and through layers of decomposition, arrived at the COMPUTER TCP layer (transmission layer). Floret computer TCP layer found that after getting the data, to confirm whether received, received package is damaged, whether in order received, etc. Of course, after packets are processed by the TCP layer, they are sent to the application layer, which then presents behaviors and actions to users based on its own protocols. For example, Floret can watch movies. We can compare the application layer to a rich young master. The TCP layer is the steward. The rich young master just told the housekeeper to send this to the goddess. The first thing the housekeeper had to do was to talk to the housekeeper of the goddess, and ask if the goddess would accept a present from our young master. If the goddess family doesn’t want to, I don’t know what to do. After the goddess also agreed, the housekeeper began to deliver goods, now the technology is not developed, carriage pull goods, biaoju one-time pull so much, so the housekeeper must first divide these things into a package, let biaoju pull again and again. But the butler doesn’t care about the delivery. Just tell me to ask you to send this package to XXX town XX village, if something is lost or broken, your biaoju can be closed. Then send me a note when they receive a package so I can clear up any packages that have already been sent. Biaoju said, “Rest assured, we have a strict protocol to ensure that your package is delivered quickly and intact.” This biaoju people get a package, the first will be most familiar with the path of the staff planning the shortest path. This is definitely the best user experience, and the shorter the path, the safer it is. The route has been mapped out, and now it’s up to the gunman to deliver. Biaoshi delivery will not directly deliver goods to the hands of the other party, but only to one of several familiar biaoshi. After all, it is a familiar place with familiar roads and people. But farther away, not necessarily. People who are not familiar with each other are prone to big problems. Biaoshi darts when a look at the number will know that they want to send the package to which points biaoju. As for the destination, gunner doesn’t care. The duty of the gunner is to ensure the safety of the goods during the delivery period. After all, no matter you take the official route or copy the road will still encounter the shameless bandits. Once hijacked darts, biaoshi have to go back to biaoju to pick up goods and send again. The goods eventually arrived in the hands of the goddess’s steward, who first made sure that each package was complete, not in the right order, and so on. Wait until all the formalities are checked before you hand it over to your young lady. Then tell the housekeeper that I have received the package. Of course, it is possible that the yard of miss is relatively small, and the delivery efficiency of biaoju is quite high, which has to tell the other housekeeper, the goods are sent slowly, my yard is not piled up. Or I want some package, it didn’t come, please send it again. In this case, biaoju plays the role of IP layer, link layer and physical layer. This document is for a quick understanding of the TCP/IP five-tier model, with a general idea in mind. I believe you to learn computer network related knowledge when it will be better to understand more.

Understand the TCP/IP protocol from the delivery story