Two network transmission Models

Two network transmission models: 1. message transmission may be large or small. If a large file is transmitted in a continuous data stream, this may mean that if a device loses part of the communication, the entire file needs to be re-transmitted and more bandwidth will be used. The solution is segment processing. Segmented messages have two main advantages: 1) multiplexing; 2) enhanced network communication efficiency. Multiplexing means that multiple communications can share one shared media. Enhanced network communication efficiency means that different segments can be sent from the source to the destination through different paths. This is a reality. The Internet always adjusts the path for efficiency. 2. For the protocol, refer to the model network professional to use two models for communication: Protocol Model and parameter model. The protocol model provides a model that precisely matches the structure of a specific protocol family. The TCP/IP model describes the functions implemented by each protocol layer in the TCP/IP protocol family. The reference model provides a general reference for consistency between various network protocols and sub-services. the reference model is mainly used to help the Group better understand the functions and processes involved. The Open System Interconnection (OSI) model is a reference model. Iii. layer-Based TCP/IP model Note: No matter what model, the lower layer is the physical layer, and the top layer is the content Layer 4) the application layer -- represents the application data for the user. 3) Transport Layer-supports communication between devices and error correction. 2) Internet layer-determine the optimal path through the network. 1) network interface layer: controls the hardware devices and media of the network. 4. TCP/IP model communication process 1. Data is created at the application layer of the source terminal device. The Application Layer sends data encoding to the transmission layer. Data is segmented and encapsulated when it is transmitted downward along the protocol family in the source terminal device. 2. Information is segmented. the transport layer adds control information (Transport Layer header) to its header so that it can be assigned to the correct process and the segments can be reorganized in order at the destination. The data segment is sent down to the Internet layer. 3. The Internet layer adds IP address information (Internet layer header) to the Data Segment header ). The data segment is now called the address package that can be processed by the router and routed to the destination. The Internet layer is sent down to the network interface layer. 4. The network interface layer establishes an Ethernet frame with lan physical address information in the header. This allows the package to arrive at the local router and to the Internet outside. The end of the frame also contains the error check information. When a frame is established, it is encoded as a bit stream that can be transmitted on the media. 5. The processing process on the target host is the opposite. Frames are encapsulated into packets, followed by segments, and finally the transport layer combines all segments in order. The header of each layer is deleted accordingly during the encapsulation process. Conclusion: 1. From the above process, we can see that data exists in different layers in different forms. The application layer -- (entire) data, transport layer -- Data Segment, Internet layer -- data packet, network Interface Layer-frame, medium-byte stream. 2. the sender sends messages from top to bottom by protocol family for encapsulation. The receiver sends messages from bottom to top by protocol family for unencapsulation. 5. OSI model layering professionals generally do not refer to the names of each layer. Second, they refer to the second layer. This is equivalent. The layer level must be clearly recorded. 7) Application Layer-provides end users with application services. 6) presentation layer-provide the data representation for the application. For example, the app layer is encrypted or encrypted as A. jpg image. 5) Session Layer-manage sessions between users. 4) Transport Layer-define data segments and numbers in the source, transfer data, and reorganize data at the destination. Add the (source, target) process number. 3) network layer-creates an end-to-end transmission and address package for intermediate devices on other networks. Add (source, target) logical network address. 2) data link layer-creates and edits the frames for sending from the host to the host or the WAN device on the LAN. Add (source, target) Physical addresses. 1) physical layer-transmits BIT data between devices. The Physical Layer Protocol defines the media specification. Timing and synchronization bit. 6. Comparing the TCP/IP model and the OSI model is a reference model with detailed details. Therefore, a layer of the protocol model generally covers multiple layers of the OSI model. The correspondence between the layers of the TCP/IP model and the layers in the OSI model is: Application Layer-application layer, presentation layer, Session Layer; Transport Layer-transport layer; Internet-network layer; Physical Layer-data link layer, physical layer.