Chapter 5: LAN ARCHITECTURE ATHENA .

Chapter 5: LAN ARCHITECTUREATHENAObjectivesIdentify the seven protocol layers of the Open System Interconnection (OSI) Reference Model Discuss the functional attributes of each layer of the Open Systems Interconnection Reference Model Understanding Putting Data on the Cable and Access MethodsATHENAContentIntroduction Open Systems Interconnection (OSI) Reference Model How network sends data Access Method SummaryATHENAIntroductionSending Data• Recognize data • Divide data into manageable chunks • Add information to each chunk– Location of data – Identify receiver• Add timing and error checking • Put data on the network and send itProtocols: procedures to send dataATHENAIntroduction (2)To solve the problem of networks being incompatible and...
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Chapter 5: LAN ARCHITECTURE ATHENA . Chapter 5: LAN ARCHITECTUREATHENA Objectives Identify the seven protocol layers of the Open System Interconnection (OSI) Reference Model Discuss the functional attributes of each layer of the Open Systems Interconnection Reference Model Understanding Putting Data on the Cable and Access MethodsATHENA Content Introduction Open Systems Interconnection (OSI) Reference Model How network sends data Access Method SummaryATHENA Introduction Sending Data • Recognize data • Divide data into manageable chunks • Add information to each chunk – Location of data – Identify receiver • Add timing and error checking • Put data on the network and send it Protocols: procedures to send dataATHENA Introduction (2) To solve the problem of networks being incompatible and unable to communicate with each other, the International Organization for Standardization (ISO) released the Open Systems Interconnection (OSI) reference model in 1984 First standard to describe architecture for dissimilar devices to communicate Best known and widely usedATHENA Open Systems Interconnection The OSI model organizes communication protocols into seven levels: • The Physical Layer • The Data Link Layer • The Network Layer • The Transport Layer • The Session Layer • The Presentation Layer • The Application LayerATHENA Open Systems Interconnection (2)ATHENA Packet Assembly & Disassembly ProcessATHENA Layer 7: The Application Layer Topmost layer Window for application processes to access network services User-end interface that support transfer files, access database, e-mail … Handles general network access, flow control, error recoveryATHENA Layer 6: The Presentation Layer Determines format to be used to exchange data Called the network translator Responsible for protocol conversion, translating data, encrypting data Manages data compression Redirector utility operates at this layerATHENA Layer 5: The Session Layer Performs name recognition and allows two applications on different computers establish, manage and end a connection (session) Provides synchronization between user tasks by placing checkpoints in the data stream Implements dialog control between communicating processesATHENA Layer 4: The Transport Layer Ensures packets are delivered error free, in sequence, no losses or duplication Repackages messages, breaking up into smaller packets Unpacks message at receiving end and sends acknowledgement Provides flow control, error handling, solves transmission problemsATHENA Layer 3: The Network Layer Addresses messages, translates logical addresses/names into physical addresses Organizes data into packets then forwards them to their destination Determines the best route on the network based on network conditions, priority of service Manages traffic problems and controls congestion of dataATHENA Layer 2: The Data Link Layer Sends data frames from network layer to physical layer Data frame: organized logical structure in which data can be placed • Simple data frame: Destination ID, Sender ID, Control, Data, CRC (cyclical redundancy check) Provides error free transfer of frames from one computer to another through the physical layerATHENA Layer 2: The Data Link Layer (2)ATHENA Layer 1: Physical Layer Responsible for the mechanical, electrical and procedural characteristics of the transmission (transmit the unstructured raw bit stream over a physical link) Establishes and maintains physical link between communication computers Defines how the cable is attached to the NIC Transmit bit (0,1) from one computer to anotherATHENA Layer 1: Physical Layer (2)ATHENA How Networks Send Data Two reasons why large chunks of data tie up network • Large chunk of data generate a problem traffic during transmission • Timely interaction and communication impossibleATHENA How Networks Send Data (2) Large Streams of DataATHENA How Networks Send Data (3) Why network divided data to packets? • Packets : small chunks/frames of dataATHENA