Advanced Computer Networks

Advanced Computer NetworksMohmmad Khalily DermanyIslamic Azad UniversityReferencesW. Stallings, Computer Networking with Internet Protocols and Technology, Pearson Prentice Hall, 2003.H. Karl, A. Willig, PROTOCOLS AND ARCHITECTURES FOR WIRELESS SENSOR NETWORKS John Wiley & Sons Ltd, 2005.Anna Hac, Wireless Sensor Network Designs, John Wiley & Sons Ltd, 2003.K. SOHRABY, D. MINOLI, T. ZNATI, WIRELESS SENSOR NETWORKS, Technology, Protocols, and Applications, John Wiley & Sons, 2007.F. Zhao, L. J. Guibas, Wireless Sensor Networks: An Information Processing Approach The Morgan Kaufmann Series in Networking, 2004.How to survive the courseSome Networking concepts are behavioral, then, do not expect everything is as exact as mathematics. Networking in general and wireless in particular is a complicated field even though it sounds easy and straightforward,Concentrates on concepts instead of a special technique or technology.The course is not a classic course like math 2, be prepared for a lot of ideas.Then, class participation is extremely important.Do not leave everything to the last minute.3General ideasWe will try to understand the wireless networking as a whole. Believe or not,, Networking is fun and applicable in many places.You are supposed to be trained as researcher, then, Be open minded, nothing is final.Try to understand the history and idea. It is important to not repeat the same thing people have done previouslyCapture concepts, then, you can easily say what is possible or not possible.Will try to follow layering perspective. Different from the book4General ideas (2)People from different background and different interests. Makes course customization difficultWireless realm is very vast, from communication to computer. It is not possible to cover everything in one semesterWe try to expose you to the whole realm without going necessarily in all detail.Notice: This course is the beginning not the end.5ProjectsGoal: new research resultsSeveral publications from last yearsInstructive projects okay tooEx: protocol visualization toolSystem building, simulation-basedTheoretical analysisMust have strong networking conceptTry to work with 12 partnersProject proposal with presentation around 5-10 minsFinal report + presentation session6Covered Topics (we try!)OverviewThe challenges, technologiesWireless FundamentalsAdhoc networkRouting for Wireless Ad Hoc Routing Wireless Sensor NetworksSpecial Topics7Why wireless networks?Mobility: to support mobile applicationsCosts: reductions in infrastructure and operating costs: no cabling or cable replacementSpecial situations: No cabling is possible or it is very expensive. Reduce downtime: Moisture or hazards may cut connections. 8Why wireless networks? (cont)Rapidly growing market attests to public need for mobility and uninterrupted accessConsumers are used to the flexibility and will demand instantaneous, uninterrupted, fast access regardless of the application.Consumers and businesses are willing to pay for it

9ReviewNetworking vs. CommunicationWhat is Networking?What is Data Communication?Whirlwind tour of networking

10History

Review (cont.)Components of a network?Distributed system with:Transmission media (coaxial cable, twisted pair (cat3, cat5), glass fiber, wireless-ether)Connectivity is the magic needed to communicate if you do not have a link.Switching elements (switch, router, node, hub, bridge, gateway )Hosts (computer, server, workstation end-system, node)Protocols (physical, link, network, transport, session, presentation, application)

12SwitchingPacket SwitchingCircuit switchingMessage switchingNetwork ArchitectureA set of layers and protocolsPeer processesthe entities making up the corresponding layers of different machines

ProtocolA protocol is a set of conventions that specifies the rules or parameters for communication between two entities (hosts, processes, switching elements, devices, etc).14entityentityNetworkProtocols specify conventions for:The type, semantics, and format of information to be conveyed between entitiesEstablishing/closing connections or sessionsRouting across a network or internetworkFlow control: speed matching between entitiesReliability: error detection, handling, correction Protocols also specifyData and object types and their representationSession characteristics (e.g., checkpointing, encryption-security, compression)Congestion detection and controlQuality of service parameters and handling

Design goalsConnectivityScalabilitySimplicityFor designers.Most importantly for users.EfficiencycostperformanceSupport for common user services.

Computer Communications Network (network, computer network)What may happen to the messages in a network?Corruptedlostduplicatedout-of-order

connection factorsTraffic data rateTraffic pattern (bursty or constant bit rate)Traffic target (multipoint or single destination, mobile or fixed)Application requirements, Delay sensitivity Loss sensitivity.

Layered ArchitectureLayer interactioneach layer offers primitive operations and services to higher layersthe interface between each pair of adjacent layers defines these primitives and servicesinterfaces should be clean and well-definedInterfacesserviceinterfaceserviceinterfacepeer-to-peer interface Protocol Entity

ProtocolEntityLayered Network ArchitectureLayer 5Layer 4Layer 3Layer 2Layer 1Host 1Layer 4/5 interfaceLayer 3/4 interfaceLayer 2/3 interfaceLayer 1/2 interfaceLayer 5 protocolLayer 5Layer 4Layer 3Layer 2Layer 1Host 2Layer 4 protocolLayer 3 protocolLayer 2 protocolLayer 1 protocolPhysical mediumProtocol Stack OperationLayers on sending side may add headers and trailers, or partition messages as they proceed down the stackLayers on receiving side remove headers and trailers, and may combine segments as they proceed up the stackLayer FunctionsEach layer may perform one or more of the following:Error controlFlow controlSegmentation and reassemblyMultiplexingConnection setupISO OSI Layered ArchitectureInternational Standards Organization Open System InterconnectionApplicationApplication specific (e.g. files)PresentationObjects (representation)SessionConversations (synchronization control)TransportMessages (reliable end-to-end transmission)NetworkPacket (routing)Data LinkFrames (construction)PhysicalRaw bitsTCP/IP layering modelInternet Reference ModelApplication - user facilities (e.g. email, ftp)Transport - reliable end-to-end transmissionInternetwork - packet formatting, routingNetwork - frame constructionPhysical - basic hardwareSome Internet ProtocolsARPANETProtocolsNetworksTELNETTCPUDPTransportLANDNSApplicationLayerPacketradioPhysical +data linkSMTPSATNETFTPIPNetworkISO OSI Reference model vs. Internet modelSeven vs. five conceptual layersprescriptive vs. descriptive modelslinear vs. non-linear

A First StepCreating a link between nodesLink: path followed by bitsWired or wirelessBroadcast or point-to-point (or both)Node: any device connected to a link29For example: Ethernet

Network Types - Direct Connectivitypoint-to-point

mulitpoint /broadcastEthernetToken RingAlso satellite/radioNetwork Types - Indirect Connectivityswitched networks

internetworksbackbonelinkhostswitchingelementTopology??