Module4- OSI Transport Layer(2)
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Transcript of Module4- OSI Transport Layer(2)
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Module 4
OSI Transport Layer
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• Roles of the Transport Layer• The TCP Protocol – Communicating with Reliability• Managing TCP Sessions• The UDP Protocol – Communicating with Low Overhead
Objectives
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Roles of the Transport Layer
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Purpose of the Transport Layer• Functions of the
Transport layer are:– Tracking the
individual communication between applications on the source and destination hosts
– Segmenting data and managing each piece
– Reassembling the segments into streams of application data
– Identifying the different applications
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Tracking the Conversations
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Segmentation
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Controlling the Conversations
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Supporting Reliable Communication
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Transport Layer Protocols• Transmission Control
Protocol (TCP)– Connection-oriented– Reliable– Divide outgoing messages
into segments– Reassembles messages at
the destination station by order
– Re-send anything not received
– Reassembles messages from incoming segments
• User Datagram Protocol (UDP)– Connectionless– Unreliable– Transmit messages– Provides no software
checking for message delivery
– Does not reassemble incoming messages by order
– Uses no acknowledgements
– Provides no flow control
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TCP and UDP
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Port Addressing
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Port Addressing• Well Known Ports
(Numbers 0 to 1023): These numbers are reserved for services and applications
• Registered Ports (Numbers 1024 to 49151): These port numbers are assigned to user processes or applications
• Dynamic or Private Ports (Numbers 49152 to 65535): Also known as Ephemeral Ports, these are usually assigned dynamically to client applications when initiating a connection
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Port Addressing
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Port Addressing
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Segmentation and Reassembly – Divide and Conquer
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The TCP ProtocolCommunicating with Reliability
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TCP – Make Conversations Reliable
TCP Segment Header Fields
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TCP Server Processes
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TCP Connection Establishment and Termination
TCP Connection Establishment
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TCP Connection Establishment and Termination
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Managing TCP Sessions
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TCP Segment Reassembly
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TCP Acknowledgement with Windowing
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TCP Retransmission
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TCP Congestion Control – Minimizing Segment Loss
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TCP Congestion Control – Minimizing Segment Loss
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The UDP ProtocolCommunicating with Low Overhead
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UDP Low Overhead vs. Reliability
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UDP Datagram Reassembly
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UDP Server Processes and Requests
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UDP Client Processes
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Good luck with this module!