osi layers

are completed by different application protocols and programs of this layer, and the differences between different network operating systems in the functions, interfaces, implementation technologies, hardware support, security reliability and various application interfaces are very large. The main functions of the application layer are as follows:User interface: The application layer is a direct interface between the user and the network, and the application and the network, allowing the user t

designed and developed into a complete, collaborative protocol series (that is, the protocol family), rather than developing each protocol in an isolated way. In the early days of network history, the International Organization for Standardization (ISO) and the International Telegraph Telephone Advisory Committee (CCITT) jointly published a layer-7 Reference Model for Open System Interconnection. Network processes in a computer operating system include application requests (at the top of the pr

data. Typical protocol representatives: RPC, SQL, NFS, NetBIOS, SCP, ASP, SSH, Winsock, BSD sockets presentation Layer (Presentation) : Transforms the upper data or information to ensure that one host application layer information can be understood by another host's application. The data transformation of the presentation layer includes data encryption, compression, format conversion, and so on. Typical protocol representatives: TIFF, GIF, JPEG, PICT, ASCII, EBCDIC, encryption, MPEG, MIDI, HT

environment.In order to make the network application more popular, ISO has introduced the OSI Reference model. The implication is that all companies are recommended to use this specification to control the network. So all companies have the same specifications, they can be connected. Computer network systems that provide a variety of Web services functions are very complex. According to the principle of divide and conquer, ISO divides the entire comm

(1) Effect(2) Codehttp://download.csdn.net/detail/wsb200514/8261547(3) Summary--You can customize the layer, especially if you want to crop the picture fillet.--The animation of the layer is the illusion, in fact, the property does not change, although the following code, but also just force the layer to stay in the last place, the actual property is still unchanged.Anim.fillmode=kcafillmodeforwards;anim.removedoncompletion=no;--Try to use UIView animations and less calayer animations.iOS develo

data. Typical protocol representatives: RPC, SQL, NFS, NetBIOS, SCP, ASP, SSH, Winsock, BSD sockets presentation Layer (Presentation) : Transforms the upper data or information to ensure that one host application layer information can be understood by another host's application. The data transformation of the presentation layer includes data encryption, compression, format conversion, and so on. Typical protocol representatives: TIFF, GIF, JPEG, PICT, ASCII, EBCDIC, encryption, MPEG, MIDI, HT

TCP/IP four layer modelTCP/IP is synonymous with a set of protocols, and it also includes many protocols that make up the TCP/IP protocol cluster. TCP/IP protocol cluster is divided into four layers, IP is located in the second layer of the Protocol cluster (corresponding to the third layer of OSI), TCP is located in the third layer of the Protocol cluster (corresponding to the fourth layer of

), i.e. the ISO open Interconnect system Reference Model. Such as. Each layer implements its own functions and protocols, and communicates with the interfaces of the neighboring layers. The OSI service definition provides a detailed description of the services provided at each level. A layer of service is the ability of the layer and its lower layers, which are

devices. . A method that ensures that network transmissions are received correctly. . How network devices maintain a constant rate of data flow. . How the electronic data is represented on the network media. The OSI model consists of 7 layers of layers: physical layer, Data link layer, network layer, transport layer, Session layer, presentation layer and app

more and more complex, and the network devices between the manufacturers are mostly incompatible and difficult to communicate.In order to solve the network compatibility problems, to help manufacturers to produce compatible network equipment, ISO in 1984, the OSI RM (Opensystem interconnection Reference model, open System Interconnect Reference Model). The OSI reference model quickly becomes the basic mode

ISO open Interconnect system Reference Model. Such as. each layer implements its own functions and protocols, and communicates with the interfaces of the neighboring layers. The OSI service definition provides a detailed description of the services provided at each level. A layer of service is a capability of the layer and its lower layers, which are passed th

Table 1-2. Table 1-2 Functions and protocols of the TCP/IP Model Level name Merit Agreement Network Interface(Host-to-net layer) Responsible for actual data transmission, corresponding to the lower two layers of the OSI reference model HDLC (Advanced Link Control Protocol)PPP (Point-to-Point Protocol)Slip (Serial Line Interface Protocol) Internet Layer(Inter-network

equipment. However, due to the coexistence of multiple protocols, the network becomes more and more complex, and the network devices between the manufacturers are mostly incompatible and difficult to communicate.In order to solve the network compatibility problems, to help manufacturers to produce compatible network equipment, ISO in 1984, the OSI RM (Opensystem interconnection Reference model, open System Interconnect Reference Model). The

The OSI reference model has many similarities with the TCP/IP reference model. They are based on the concept of an independent protocol stack. In addition, the features of the layer are similar. For example, in the two models, the transmission layer and above all provide end-to-end and network-independent transmission services for processes that want to communicate. These layers form a transport provider. S

OSI network layer-7 protocol and its functions OSI is an open reference model for communication between systems. It is a well-defined protocol specification. The OSI model has a layer-7 structure, and each layer can have several child layers. Next I will briefly introduce these 7 l