Computer Network Protocols 4th Grade 2022-2023 PDF

Computer Network protocols 4th Grade 2022-2023 Dr. Mohammed Hasan Ali Source & References 1.Computer Networks, Andrew S. Tanenbaum 2. top to down-computer networking, James Kurose. 3. Network communication, Bahrus Introduction NETWORK ARCH...

Computer Network protocols 4th Grade 2022-2023 Dr. Mohammed Hasan Ali Source & References 1.Computer Networks, Andrew S. Tanenbaum 2. top to down-computer networking, James Kurose. 3. Network communication, Bahrus Introduction NETWORK ARCHITECTURES: A set of layers and protocols is called the network architecture. PROTOCOL HIERARCHIES Networks are organized as layers to reduce design complexity. Each layer offers services to the higher layers. Between adjacent layers is an interface. Services – connection oriented and connectionless. Interface – defines which primitives and services the lower layer will offer to the upper layer. Primitives – operations such as request, indicate, response, confirm DESIGN ISSUES FOR THE LAYERS(FUNCTIONS) Mechanism for connection establishment Rules for data transfer Error control Fast sender swamping a slow receiver Inability of processes to accept long messages Routing in the case of multiple paths Why a layered model? –Easier to teach communication process. –Speeds development, changes in one layer does not affect how the other levels works. –Allows different hardware and software to work together. –Reduces complexity –Breaks down communication into smaller, simpler parts. Protocol It is a format order of messages sent and received among the net entities and action taken on messages transmission receipt. Protocol process: The format or structure of the message The process by which networking devices share information about pathways with other networks How and when error and system messages are passed between devices The setup and termination of data transfer sessions The OSI model (open system interconnection) – is a theoretical blueprint that helps us understand how data gets from one user‟s computer to another. –It is also a model that helps develop standards so that all of our hardware and software talks nicely to each other. Q. Why use a reference model? –Serves as an outline of rules for how protocols can be used to allow communication between computers. –Each layer has its own function and provides support to other layers. Q. What are Other reference models being in use? –Most well-known is the TCP/IP reference model. –We will compare OSI and TCP/IP models 1.Physical Layer a) Convert the logical 1’s and 0’s coming from layer 2 into electrical signals. b) Transmission of the electrical signals over a communication channel. 2. Data Link Layer a) Error control to compensate for the imperfections of the physical layer. b) Flow control to keep a fast sender from swamping a slow receiver. 3. Network Layer a) Controls the operation of the subnet. b) Routing packets from source to destination. c) Logical addressing. 4. Transport Layer a) Provides additional Quality of Service. b) Heart of the OSI model. 5. Session Layer a) Allows users on different machines to establish sessions (dialogue) between them. b) One of the services is managing dialogue control. c) Token management. d) Synchronization. 6. Presentation Layer a) Concerned with the syntax and semantics of the information. b) Preserves the meaning of the information. c) Data compression. d) Data encryption. 7. Application Layer Provides protocols that are commonly needed.  SERVICES OF OSI 1. Connection-Oriented and Connectionless Connection-Oriented – before data is sent, the service from the sending computer must establish a connection with the receiving computer. Connectionless – data can be sent at any time by the service from the sending computer. 2. Service Primitives Request entity wants the service to do some work Indicate – entity is to be informed about an event Response – entity responds to an event Confirm – entity is to be informed about its request