EL5363 WK1 Lecture Protocol Architecture

EL5363 WK1 Lecture Protocol Architecture - Protocol...

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Unformatted text preview: Protocol Architecture Click to edit Master subtitle style 11 Outline Why protocol n Design principles n TCP/IP n Communication Networks of NYU © Kang Xi, Polytechnic Institute 22 Foundations of Communication n Connectivity ¨ Moving bits from one device to another n Agreements ¨ Common knowledge between individuals in communication ¨ Know how to react to a received data Communication Networks of NYU © Kang Xi, Polytechnic Institute 33 Protocols for Conversation n n n Share the same language Conversation w/o collision: speak+listen Some common knowledge Communication Networks of NYU © Kang Xi, Polytechnic Institute 44 Protocols for Telegram NYC EL536 is boring EL536 is boring LA 2155 5523 … n Protocols: ¨ Encoding/decoding rules ¨ Starting/ending of a telegram Communication Networks of NYU © Kang Xi, Polytechnic Institute 55 Decomposition for complexity Complex System subsys subsys subsys subsys Communication Networks of NYU © Kang Xi, Polytechnic Institute 66 Communication protocol Communication is a tandem system n Pick out a certain section as an function entity n Decompose the whole system into a set of protocols n user1 tx channel rx user2 Communication Networks of NYU © Kang Xi, Polytechnic Institute 77 Layered Architecture Application Application Transport Transport A layer Network Access Network Access Communication Networks of NYU © Kang Xi, Polytechnic Institute 88 Principles for layering n n n Functionality ¨ Group ¨ Not similar functions into the same layer Simplicity too many, not too few layers layer is relatively independent Scalability ¨ Each Communication Networks of NYU © Kang Xi, Polytechnic Institute 99 Network Access Layer Exchange of data between the computer and the network n Sending computer provides address of destination n May invoke levels of service n Dependent on type of network used (LAN, packet switched etc.) n Communication Networks of NYU © Kang Xi, Polytechnic Institute 1010 Transport Layer Reliable data exchange n Independent of network being used n Independent of application n Communication Networks of NYU © Kang Xi, Polytechnic Institute 1111 Application Layer Support for different user applications n e.g. e-mail, file transfer n Communication Networks of NYU © Kang Xi, Polytechnic Institute 1212 Protocol Architectures and Networks Communication Networks of NYU © Kang Xi, Polytechnic Institute 1313 Protocol Data Units (PDU) At each layer, protocols are used to communicate n Control information is added to user data at each layer n ¨ Basic: destination address Is it enough to attach nothing but the destination address? Communication Networks of NYU © Kang Xi, Polytechnic Institute 1414 Network PDU n Adds network header ¨ network address for destination computer ¨ Facilities requests Communication Networks of NYU © Kang Xi, Polytechnic Institute 1515 Operation of a Protocol Architecture Communication Networks of NYU © Kang Xi, Polytechnic Institute 1616 Standardized Protocol Architectures n n n n Required for devices to communicate Vendors have more marketable products Customers can insist on standards based equipment Two standards: ¨ ¨ OSI Reference model n Never lived up to early promises Most widely used TCP/IP protocol suite n n Also: IBM Systems Network Architecture (SNA) Communication Networks of NYU © Kang Xi, Polytechnic Institute 1717 TCP/IP Protocol Suite n n n n Developed by the US Defense Advanced Research Project Agency (DARPA) for its packet switched network (ARPANET) Used by the global Internet No official model but a working one. Five layers: ¨ ¨ ¨ ¨ ¨ Application layer Host to host or transport layer Internet layer Network access layer Physical layer © Kang Xi, Polytechnic Institute 1818 Communication Networks of NYU OSI vs TCP/IP Communication Networks of NYU © Kang Xi, Polytechnic Institute 1919 TCP/IP Layers n Physical Layer Physical interface between data transmission device (e.g. computer) and transmission medium or network ¨ Characteristics of transmission medium ¨ Signal levels ¨ Data rates ¨ n Network Access Layer Exchange of data between end system and network ¨ Destination address provision ¨ Invoking services like priority ¨ Communication Networks of NYU © Kang Xi, Polytechnic Institute 2020 TCP/IP Layers n Internet Layer (IP) Systems may be attached to different networks ¨ Routing functions across multiple networks ¨ Implemented in end systems and routers ¨ n Transport Layer (TCP) Reliable delivery of data ¨ Ordering of delivery ¨ n Application Layer Support for user applications ¨ e.g. http, SMTP ¨ Communication Networks of NYU © Kang Xi, Polytechnic Institute 2121 TCP/IP Protocol Suite n The complete TCP/IP protocol suite contains many protocols. The following graph is far from complete Communication Networks of NYU © Kang Xi, Polytechnic Institute 2222 Obj100 TCP/IP Concepts FTP: 21, Telnet: 23, Http: 80, SMTP: 25, POP: 110 192.168.1.1 Mac: 00-05-4E-44-88-AB Communication Networks © Kang Xi, Polytechnic Institute 2323 of NYU PDUs in TCP/IP n Example Header Information ¨ Destination port ¨ Sequence number ¨ Checksum Communication Networks of NYU © Kang Xi, Polytechnic Institute 2424 ...
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