02-ProtocolArchitecture - Data and Computer Communications...

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Unformatted text preview: Data and Computer Communications Communications Chapter 2 – Protocol Architecture, Chapter TCP/IP, and Internet-Based Applications Applications Eighth Edition by William Stallings Lecture slides by Lawrie Brown Protocol Architecture, TCP/IP, and Internet-Based Applications Applications To destroy communication completely, there To must be no rules in common between transmitter and receiver—neither of alphabet nor of syntax —On Human Communication, nor Colin Cherry Colin Need For Protocol Protocol Architecture Architecture data exchange can involve complex data procedures, cf. file transfer example procedures, better if task broken into subtasks implemented separately in layers in stack each layer provides functions needed to each perform comms for layers above perform using functions provided by layers below peer layers communicate with a protocol Key Elements of a Protocol Key syntax - data format semantics - control info & error handling timing - speed matching & sequencing TCP/IP Protocol Architecture TCP/IP developed by US Defense Advanced developed Research Project Agency (DARPA) for ARPANET packet switched network used by the global Internet protocol suite comprises a large collection protocol of standardized protocols of Simplified Network Architecture Architecture TCP/IP Layers TCP/IP no official model but a working one no Application layer Host-to-host, or transport layer Internet layer Network access layer Physical layer Physical Layer Physical concerned with physical interface between concerned computer and network computer concerned with issues like: characteristics of transmission medium signal levels data rates other related matters Network Access Layer Network exchange of data between an end system exchange and attached network and concerned with issues like : destination address provision invoking specific services like priority access to & routing data across a network link access between two attached systems between allows layers above to ignore link specifics Internet Layer (IP) Internet routing functions across multiple networks for systems attached to different networks using IP protocol implemented in end systems and routers routers connect two networks and relays routers data between them data Transport Layer (TCP) Transport common layer shared by all applications provides reliable delivery of data in same order as sent commonly uses TCP Application Layer Application provide support for user applications need a separate module for each type of need application application Operation of TCP and IP Operation Addressing Requirements Addressing two levels of addressing required each host on a subnet needs a unique each global network address global its IP address each application on a (multi-tasking) host each needs a unique address within the host needs known as a port Operation of TCP/IP Operation Transmission Control Protocol (TCP) usual transport layer is (TCP) provides a reliable connection for transfer of provides data between applications data a TCP segment is the basic protocol unit TCP tracks segments between entities for TCP duration of each connection duration TCP Header TCP User Datagram Protocol User (UDP) an alternative to TCP no guaranteed delivery no preservation of sequence no protection against duplication minimum overhead adds port addressing to IP UDP Header UDP IP Header IP IPv6 Header IPv6 TCP/IP Applications TCP/IP have a number of standard TCP/IP have applications such as applications Simple Mail Transfer Protocol (SMTP) File Transfer Protocol (FTP) Telnet Some TCP/IP Protocols Some OSI OSI Open Systems Interconnection developed by the International developed Organization for Standardization (ISO) Organization has seven layers is a theoretical system delivered too late! TCP/IP is the de facto standard OSI Layers OSI OSI v TCP/IP OSI Standardized Protocol Architectures Architectures Layer Specific Standards Layer Service Primitives and Parameters Parameters define services define between adjacent layers using: layers primitives to specify primitives function performed function parameters to pass parameters data and control info data Primitive Types Primitive REQUEST A primitive issued by a service user to invoke some service and to pass the parameters needed to specify fully the requested service INDICATION A primitive issued by a service provider either to: indicate that a procedure has been invoked by the peer service user on the connection and to provide the associated parameters, or notify the service user of a provider-initiated action RESPONSE A primitive issued by a service user to acknowledge or complete some procedure previously invoked by an indication to that user CONFIRM A primitive issued by a service provider to acknowledge or complete some procedure previously invoked by a request by the service user Traditional vs Multimedia Applications Applications traditionally Internet dominated by info traditionally retrieval applications retrieval typically using text and image transfer eg. email, file transfer, web see increasing growth in multimedia see applications applications involving massive amounts of data such as streaming audio and video such Elastic and Inelastic Traffic Elastic elastic traffic can adjust to delay & throughput changes can over a wide range over eg. traditional “data” style TCP/IP traffic some applications more sensitive though inelastic traffic does not adapt to such changes eg. “real-time” voice & video traffic need minimum requirements on net arch Multimedia Technologies Multimedia Summary Summary introduced need for protocol architecture TCP/IP protocol architecture OSI Model & protocol architecture OSI standardization standardization traditional vs multimedia application needs ...
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