Hierarchical distribution of important TCP Protocols

On the Internet, we can play games or watch movie animations online. It is even more difficult to process some documents. So how does it do it? These also need to rely on the role of the tcp ip protocol. However, the tcp ip protocol is not only a collection of many protocols. We have learned about the OSI reference model before. Now let's take a look at how the tcp ip protocol implements the network model compared with the layer-7 Protocol Reference Model ｡

OSILayer in	Function	TCP/IPProtocol family
Application Layer	File transmission, email, file service, virtual terminal	TFTP, HTTP, SNMP, FTP, SMTP, DNS, Telnet
Presentation Layer	Data formatting, code conversion, and Data Encryption	No agreement
Session Layer	Release or establish contact with other contacts	No agreement
Transport Layer	Provides end-to-end Interfaces	TCP, UDP
Network Layer	Select a route for a data packet	IP, ICMP, RIP, OSPF, BGP, IGMP
Data Link Layer	Transmitted frame with address and Error Detection Function	SLIP, CSLIP, PPP, ARP, RARP, MTU
Physical Layer	Transmit data on physical media in the form of binary data	ISO2110, IEEE802. 802.2

The data link layer includes hardware interfaces and protocols ARP and RARP. These two protocols are used to establish information sent to the physical layer and receive information uploaded from the physical layer;

The protocols at the network layer mainly include IP, ICMP, and IGMP. because they contain IP protocol modules, they are the core of all opportunities for the TCP/IP protocol network, the IP module completes most of the functions. ICMP, IGMP, and other protocols that support IP addresses help IP addresses complete specific tasks, for example, transmission error control information and control messages between hosts and routers. The network layer is in charge of information transmission between hosts in the network ｡

The main protocols on the transport layer are TCP and UDP. Just as the network layer controls data transmission between hosts, the Transport Layer controls the data that will enter the network layer. Two protocols are used to manage the data: TCP is a connection-based protocol. (Do you still remember the connection-oriented service and connection-free service concepts we mentioned in the network basics? If you forget it, check it out.) UDP is a management protocol for the connectionless service ｡

The application layer is at the top of the protocol stack, and its main task is to apply. The above Protocol is also designed for these applications. Specifically, some common protocol functions are as follows:

Telnet: provides remote login (terminal simulation) service. It seems that the old BBS is used for this login ｡

FTP: provides application-level file transfer services, which are simple and clear: Remote File Access and other services;

SMTP: The E-mail protocol used every day ｡

TFTP: provides a small and simple File Transfer Service. In fact, it is a replacement for FTP from a certain perspective (when the file is very small and only needs to be transferred )｡

SNTP: Simple Network Management Protocol. It doesn't have to be said by name ｡

DNS: The domain name resolution service, that is, how to map domain names to city IP addresses ｡

HTTP: Are you familiar with this protocol? This is a hypertext transfer protocol. The reason why you can see images, animations, audios, and so on the internet is that the HTTP in this TCP/IP protocol is working!