Slide 1Mobile, Wireless DevicesWhy Study Mobile Networking?AcademiaChallenges of Mobile NetworkingProtocol StackMobile Networking Topics: Lecture OutlineSlide 8Mobile Host on the InternetIP AddressesMobile Host on the InternetMobile IP SolutionMobile IP SolutionRoute OptimizationSlide 15Ad-hoc NetworksAd-hoc NetworksAd-hoc NetworksRouting Protocol CategoriesRouting Protocol CategoriesReactive ProtocolsDynamic Source Routing (DSR) From Shweta Jain’s SlidesRoute Discovery in DSRRoute Discovery in DSRRoute Discovery in DSRRoute Discovery in DSRRoute Reply in DSRRoute Caching in DSRData Delivery in DSRRoute ErrorRoute ErrorRoute ErrorAggressive Route CachingContents of Caches on Selected Nodes After one RREQ-RREP CycleUse of Route CachingRoute Caching: Beware!Dynamic Source Routing: AdvantagesDynamic Source Routing: DisadvantagesDynamic Source Routing: DisadvantagesSlide 40AODVAODV Route DiscoveryAODV Route DiscoveryAODV Route DiscoveryAODV Route DiscoveryAODV Route DiscoveryAODV Route DiscoveryRoute Expiry on TimeoutRoute ExpiryLink Failure DetectionRoute ErrorRoute Error PropagationRoute Error PropagationRoute Error PropagationRoute Error PropagationPossibility of Routing Loops!Possibility of Routing Loops!Use of Sequence Numbers in AODVUse of Sequence Numbers in AODVHow Using Sequence Numbers can Avoid Loop?Summary: AODVFlood Control OptimizationFlood Control OptimizationProactive ProtocolsLink State RoutingTypes of DiscoveryLink State AlgorithmOLSR: Optimized Link-State RoutingTraditional FloodingMultipoint RelaysOptimized Link State Routing (OLSR)Slide 72Disruption Tolerant NetworksNo Reliance on InfrastructureRouting ConsiderationsRouting CategoriesEpidemic RoutingSynchronizingPros and ConsMaxPropMaxPropMeeting ProbabilitiesPath Cost CalculationComplementary MechanismsSpray and WaitExamplePros and ConsEncounter-Based RoutingMeasuring PopularityDistributing QuotaExampleExampleExamplePros and ConsConclusionsOverview of Mobile NetworkingSam NelsonSome slides borrowed from Prof. Ray and Prof. JainMobile, Wireless Devices•Goals–Allow communication to and from the Internet to mobile devices–Allow mobile devices in the same area to talk without going through infrastructureMobile wireless communication devices are becoming ubiquitousSmart phonesEmergency responseVehiculartechnologyWhy Study Mobile Networking?•WapReview : The total number of mobile Internet users: 1.05 billion, which in 2008 for the first time surpassed the total number of PC Web users (1 billion)•DigitalStats : (June 2009) In the last six months, uploads from mobile phones to YouTube jump by 1700%.•DigitalStats : When posed with the question "Which do you access Social Network sites from more, mobile phone or computer?”(Sample size=321, Japanese survey)–Computer 14.0%–Mobile phone 70.4%–Both about the same 15.0%–Don’t know 0.6%Academia•Top conferences with interests in mobile computing:–ACM MobiCom–IEEE InfoCom–ACM Sigcomm–NSDI–IEEE SECON–ICDCSChallenges of Mobile Networking•Topology can change very quickly–New links form and break–Nodes leave and join the system•Mobility occurs in the wireless domain–Interference–Propagation issues–Spectrum regulation and use•End-to-end paths may not actually existProtocol StackPhysicalPhysicalLinkLinkNetworkNetworkTransportTransportApplicationApplicationWireless propagation issuesInterference / Hidden terminalEstablishing routes / addressingReliable, in-order delivery / congestion controlSensing / emergency response, social networkingLayerLayerMobility ChallengesMobility ChallengesMobile Networking Topics:Lecture OutlineMobile Clients on the InternetMobile Clients on the InternetMobile Ad-hoc Networks (MANETs)Mobile Ad-hoc Networks (MANETs)Delay-Tolerant Networks (DTNs)Delay-Tolerant Networks (DTNs)- Communicate to/from Internet- Infrastructure in 1-hop- Addressing Problems- Communicate to/from Internet- Infrastructure in 1-hop- Addressing Problems- Communicate within network- No infrastructure- Relatively high connectivity- Communicate within network- No infrastructure- Relatively high connectivity- Communicate within network- No infrastructure- Low connectivity- Communicate within network- No infrastructure- Low connectivityMobile Clients on the InternetMobile Host on the Internet•Goal: Maintain two-way connectivity to Internet and a mobile host.Net ANet ANet BNet BInternetInternetIP_AFor IP_AIP Addresses•What do IP addresses really mean?213.86.83.116 / 8NetworkHostIP address is for routing purposesIP address is for routing purposesHence, they must change when a node changes networksHence, they must change when a node changes networksIP addresses are topologically dependent and hence are bad choices for long lasting names in mobile environments IP addresses are topologically dependent and hence are bad choices for long lasting names in mobile environmentsMobile Host on the Internet•Solutions?–Change IP address  Connectivity is lost… what is host’s IP?–Keep IP address  Routing will fail... host not found.How can S send to the moved mobile host?How can S send to the moved mobile host?Net ANet ANet BNet BInternetInternetIP_A IP_BFor IP_AMobile IP Solution•Mobile host keeps it’s old IP address, and gets someone to forward messages to it•It must inform this “someone” of it’s new address•Agents to help – home agent and foreign agentOld IPOld IPNew IPNew IPReferred to as “home address”Referred to as “care-of address”Mobile IP SolutionHNR1 R3FN FNR2HAMHMHCHFAMobile Host:a host or router capableof changing its point ofattachment to the InternetForeign Network:a network, other than MA’s homenetwork, that MH is currently attachedto.Corresponding Host:a host or router communicationgwith a mobile node.Home Network:the network identifiedwith a mobile nodeHome Address:MH’s permanent IP address, network ID of this address identifies the mobile’s home network.Home Agent:a router attached to the MH’s home networkmaintains current location information for the MHis responsible for forwarding packets destined for theMH when MH is away from home.Foreign Agent (FA)a router in the foreign network that the MH is visiting provides routing services to the MH; may serve as default router for outgoing packet from MHRoute OptimizationRoute Optimization•Triangular routing–Data goes from source to Home Agent to mobile device (or foreign agent)–Reverse path is different – Data goes from mobile