Introduction to Computer Networks (R2)

Introduction to Computer Networks (R2) - CSCI 232 -...

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Unformatted text preview: CSCI 232 - Computer Networks Introduction to Computer Networks CSCI 232 Computer Networking: Introduction to Computer Networks George Blankenship Introduction to Computer Networks George Blankenship 1 Lecture Outline • Environment – Business relationships – Technology relationships • Terminology • Topology – Logical relationships – Physical relationships • Architecture • Standards organizations Introduction to Computer Networks George Blankenship 2 The Changing World of Communication • Past – Business separation between communications and data processing • Present – Data processing and data communications hardware is the same – Data, voice, and video communications are fundamentally the same – The distinction between intra-processor and interprocessor technology has blurred Introduction to Computer Networks George Blankenship 3 George Blankenship 1 CSCI 232 - Computer Networks Introduction to Computer Networks Communication Objective • Movement of information from source to destination • Information movement attributes – – – – Accuracy - received what was sent Reliability - performs predictably Intelligible - able to understand what was sent Availability - usable by those that have need George Blankenship 4 Introduction to Computer Networks Communication Model • Source • Transmitter – Physical (hardware encoding) – Logical (software encapsulation) • Transmission facility – Physical (hardware) – Logical (queue) • Receiver – Physical (hardware decoding) – Logical (software decapsulation) • Destination Introduction to Computer Networks George Blankenship 5 Communication Terms • • • • • • • Interface Signal generation Exchange management/flow control Error detection/recovery Message formatting Transmission system utilization Management George Blankenship 6 Introduction to Computer Networks George Blankenship 2 CSCI 232 - Computer Networks Introduction to Computer Networks Security • Reliability and integrity – Prevention of lost data – Prevention of duplicate data – Prevention of introduction of errors • Privacy and assurance – Authentication of source and destination – Authentication of content – Hiding content • Confidentiality, Integrity, and Assurance Introduction to Computer Networks George Blankenship 7 Topological Configuration • Broadcast – Works well in a regulated environment • Point-to-point – Appropriate for two devices – Difficult for more than two devices [(n2) circuits] • Multiplexing – Inappropriate for two devices – Interconnection of multiple devices – Multiplexing strategy • Media sharing • Multiple media Introduction to Computer Networks George Blankenship 8 Network Categories • Local area network (LAN) – Narrow geography – Short latency • Wide area network (WAN) – Wide geography – Long latency Introduction to Computer Networks George Blankenship 9 George Blankenship 3 CSCI 232 - Computer Networks Introduction to Computer Networks LAN Implementation • Broadcast – – – – All members of LAN “see” all messages Multiplexing is does not require active components Multiplexing is time based Shared media (fixed and wireless) • Packet switched – Messages are broken into packets – Data streams are based upon the underlying messages Introduction to Computer Networks George Blankenship 10 Wide Area Technologies • Circuit switching – Reservation based multiplexing – Clear channel – Connection oriented communication • Packet switching – Statistical based multiplexing – Each packet introduces burden – Connectionless communication Introduction to Computer Networks George Blankenship 11 WAN Implementation • • • • • The network spans the globe X.21 - circuit switching X.25 - packet switching Frame relay - X.25 derivative ATM - frame relay with fixed length frames ISDN - circuit switching with out of band signaling George Blankenship 12 Introduction to Computer Networks George Blankenship 4 CSCI 232 - Computer Networks Introduction to Computer Networks Protocol and Protocol Architecture • Protocol defines how two entities communicate (exchange information) • Protocol architecture defines a set of protocols and the services that are supplied • Each entity pair uses protocol to communicate (human language) • Each entity uses a service definition for another entity pair to actually communicate Introduction to Computer Networks George Blankenship 13 Protocol Taxonomy • Syntax – Encoding rules • Semantics – Meaning rules • Timing – Sequence rules Introduction to Computer Networks George Blankenship 14 Protocol Architecture Taxonomy • Service definition – Capability provided by the entity pair • Service interface – Protocol used to access service – Syntax, semantics and timing required to use the service Introduction to Computer Networks George Blankenship 15 George Blankenship 5 CSCI 232 - Computer Networks Introduction to Computer Networks Layered Protocol Architecture • Communication divided into basic building blocks (layers) • Allows focus on properties of individual layer and services required • PDU (protocol data unit) - information unit between pairs • SDU (service data unit) - information unit between requestor and service provider Introduction to Computer Networks George Blankenship 16 Seven Layer Architecture OSI Model • • • • • • • Physical Link Network Transport Session Presentation Application George Blankenship 17 Introduction to Computer Networks Three Layer Architecture • Network – Physical movement of data – Multiplexing focus • Transport – Movement of data between source and destination – Reliability focus • Application Introduction to Computer Networks George Blankenship 18 George Blankenship 6 CSCI 232 - Computer Networks Introduction to Computer Networks TCP/IP • IP (network) – Physical connections – Multiplexing (routing - internet) • TCP (transport) – Host-to-host connections – Reliability (error detection and recovery) • FTP (application) Introduction to Computer Networks George Blankenship 19 TCP/IP Standards Groups • • • • • Membership is informal IAB - overall direction IETF - technical direction IESG - standard tracking RFC - document with proposed architecture component • STD (IEN) - standardized architecture component Introduction to Computer Networks George Blankenship 20 ISO Organization of the standards groups of each nation – US standards group is ANSI – Voluntary membership • DP - draft proposal • DIS - draft international standard • IS - international standard Introduction to Computer Networks George Blankenship 21 George Blankenship 7 CSCI 232 - Computer Networks Introduction to Computer Networks ITU • UN sponsored organization – US member is department of state – Defined interconnection of telephone networks • Draft recommendation - proposal for change • Recommendation - defined standard • ITU plenary sessions meet every four years Introduction to Computer Networks George Blankenship 22 Reading and Thought • Web page for Tanenbaum text book: http://authors.phptr.com/tanenbaumcn4/ • Tanenbaum – Review chapter 1 – Read chapter 2 Introduction to Computer Networks George Blankenship 23 George Blankenship 8 ...
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