Shulou(Shulou.com)06/01 Report--

We should know that the process of data transmission between networks is very complex, so we should first establish a hierarchical model, which is a set of design methods for developing network protocols, that is, the complex problem of communication between nodes in the network is layered into several relatively simple problems, each problem corresponds to a layer, each layer implements certain functions, and the complex task of data communication can be completed by cooperating with each other.

OSI reference model

OSI (Open System Interconnect) Open Systems Interconnection reference Model is an open architecture issued by ISO (International Standards Organization), which divides the network into seven layers.

Stratification

An interface between the functional application layer network service and the end user data format conversion coding, data compression and decompression, data encryption and decryption and other session layers allow users on different hosts to establish, manage and terminate the session transport layer to divide the upper layer data into data segments, define the protocol port number, and realize the data communication network layer between different host user processes to encapsulate the upper layer data into data packets. Logical address addressing, path selection between different networks, data link layer encapsulates the last data into a fixed format frame, physical layer physical connections such as hardware address addressing, error checking, etc., to complete the transmission of the original bit stream between adjacent nodes.

TCP/IP reference model

TCP/IP is a collection of a series of models. The early TCP/IP model has a four-tier structure. Later, it draws lessons from OSI's seven-tier reference model to form a new five-tier structure.

TCP/IP four-layer model TCP/ IP five-layer model OSI seven-layer model

Application layer

Application layer

Application layer presentation layer session layer transport layer network layer

Network interface layer

Data link layer physical layer physical layer

Common protocols and equipment of TCP/IP layer 5 Protocol

Today's networks are mostly based on TCP/IP protocol, all people use TCP/IP hierarchical model to analyze and solve problems in practical work, while TCP/ IP five-layer model is more widely used.

TCP/IP five-layer model typical hardware equipment application layer HTTP, FTP, TFTP, SMTP, SNMP, DNS computer transport layer TCP, UDP firewall network layer ICMP, IGMP IP ARP, RARP router data link layer protocol switch physical layer defined by the underlying network protocol network card defined by the underlying network

Protocol data unit PDU in the process of data transmission when data is encapsulated and unencapsulated.

Data encapsulation process

Data unencapsulation process

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.