osi model pdu

1. The reference model of Iso/osi has 7 layers , from low to high level: physical layer, Data link layer, network layer, transport layer, Session layer, presentation layer ,Application Layer . The functions of each layer are:(1) Physical layer provides the mechanical, electrical, functional and procedural characteristics required to establish, maintain, and dismantle physical links; Provides information abo

Introduction to the OSI Layer-7 Model OSI is an open reference model for System Interconnection. It is a well-defined protocol specification. The OSI model has a layer-7 structure, and each layer can have several child layers. Nex

The OSI Reference Model: The ISO/IEC 7498 standard defines a 7-tier architecture model for network interconnection, the Open Systems Interconnect Reference Model.The OSI Reference Model defines the hierarchical structure of open systems, the interrelationships between hierar

segments are separated at this layer. encapsulation is called packet. There are two types of packages. One is data packets, which is the user data transmitted from the upper layer; the other type is route update packets, which is directly sent by the router and used to exchange route information with other routers. The data link layer prepares physical transmission, CRC verification, Error Notification, network topology, and traffic control. The well-known MAC addresses and switches work on thi

Introduction: Before 1990, the hierarchical model dominated by data communication and networking literature was the Open Systems Interconnection (open system Interconnection,osi) model, and now the TCP/IP protocol family became the dominant commercial architecture. An OSI seven-layer

OSI reference model Introduction: Open System Interconnection (OSI) is an open reference model for interconnection of traffic systems. It is a well-defined protocol specification. The OSI model has a layer-7 structure, and ea

Many training institutions and training tutorials have taken the "OSI Reference Model" as the beginning of the curriculum, which is a very important foundation for our learning network. The following is the OSI structure diagramOSI: Layer Seventh Application layer (application)Sixth Layer Presentation layer (Presentation)Level fifth sessionFourth layer Transport

Friends who are interested in network programming may have heard of the OSI seven layer model, and the next one is a diagram of the entire protocol implemented under Windows. Implementation structure of the OSI seven layer model under Windows +-------------------------------+ | Ws2_32.d

The correspondence between the OSI model and the TCP/IP protocol the layers of popular TCP/IP protocols are not divided by the OSI reference model, but have a general correspondence with them. Network layer protocols mainly include the IP protocol to encapsulate and send IP packets. Grouping routing and avoiding blocki

Tag:httpioosarsp Data divon code The Http://baike.baidu.com/view/69334.htmMAC (Media Access Control) address, or MAC location, is used to define the locations of network devices. In the OSI model, the third layer of the network layer is responsible for the NBSP;IP address, while the second layer of data link is responsible for MAC addresses. Therefore, a host will have an IP address, and each network locat

repeater with multiple ports is a hub (for example, if the transmission distance of twisted pair wires is m and the signal length exceeds the whole length, the communication fails. In this case, we need a repeater to expand the signal !).Conclusion: In the osi7 layer protocol, when user a communicates with user B Over FTP, user a first activates port 21 of the application layer and requires that user a provide file transfer services for themselves. After port 21 is activated, send the data to t

Over FTP, user a first activates port 21 at the application layer and needs to provide file transfer service for himself, After port 21 is activated, the data is sent to the presentation layer. The presentation layer encrypts and compresses the data, and then the presentation layer submits the data to the Session Layer. The Session Layer establishes a session and ends a session, but establishes a session, end the session. If you do not implement the session, you only need to manage the session

　　　　　　　　　　　Network programmingNetwork model: OSI (Open System Interconnection Open System interconnect) Reference Model TCP/IP Reference Model Seven Floor Brief:1. Layer Physical layer: The main definition of physical equipment standards, such as the interface type of network cable, the interface type

Layer function in OSI TCP/IP protocol familyApplication layer File transfer, e-mail, file service, virtual terminal tftp,http,snmp,ftp,smtp,dns,telnetpresentation layer data formatting, code conversion, data encryption no protocolsession layer lifted or established contact with other Contacts no protocolThe transport layer provides an end-to-end interface to the TCP,UDP network layer for packet selection routing IP,ICMP,RIP,OSPF,BGP,IGMP the data link

between a-B and the reliability of the connection4) package The data at the network layer and define the destination IP address and source IP address in front of the packaged data5) Reprocessing at the data link layer, the data mask after processing defines the target Mac and source MAC address6) Re-physical layer, eventually changing the data to machine and identification of the 10101 binary encoding, and then transmission on the network cable7) to the router to the data forwarding, in order t

1.UDP protocolUDP is a connectionless transport layer protocol in the OSI Reference Model, which is mainly used for transport that does not require packet order arrival, and the packet transmission sequence is completed by the application layer [2], providing a simple and unreliable information delivery service for transactions. The UDP protocol is basically the interface between IP protocol and upper layer

representation, implementation of specific functions, such as encryption and decryption (Ascii,mp4 ... ）。Session Layer: Managing the application session, synchronizingTransport Layer: Reliable (TCP) and unreliable (UDP) transmissions, pre-transmission detection, flow controlNetwork layer: Provides logical address (IP), routingData link layer, frame, access media with MAC address, error detection and correctionPhysical layer: The transmission of bits (machine language) between devices, physical

OSI Virtual machine model "Virtual" is to hint at a certain time, although an object or device does not exist, but people can see it The word "virtual machine" is easy for many people to have a rich association. The word "virtual" is often used in popular media and news broadcasts when reporting on new developments in computer simulations and computer games. In either case, the use of "virtual" is sug

Layer description The application layer provides the corresponding interface for users to use the network connection function.The presentation layer completes data formattingThe Session Layer controls the communication links between two hosts (open, operate, and close)The transport layer provides data transmission services (reliable or unreliable)The network layer provides a addressing/addressing mechanism between two hosts and is responsible for packet routing.The data link layer controls the

First, the physical layer1. Responsible for the transmission of the bit stream between the equipment, physical interface, electrical characteristics and so on.It's not, it's only 1, 3, 2, 64 lines for transmitting data, the rest of the line doesn't matter,Similar functions are controlled by the physical layer.2. Most common devices in the physical layerSecond, Data link layer1. The main function of data link layer is to encapsulate frame, access media with MAC address, error detection and correc