Chapter 6 outlineWhat is mobility?Mobility: vocabularyMobility: more vocabularyHow do you contact a mobile friend:Mobility: approachesSlide 7Mobility: registrationMobility via indirect routingIndirect Routing: commentsIndirect routing: moving between networksMobility via direct routingMobility via direct routing: commentsAccommodating mobility with direct routingSlide 15Mobile IPMobile IP: indirect routingMobile IP: agent discoveryMobile IP: registration examplePowerPoint PresentationHandling mobility in cellular networksSlide 22Slide 23Slide 24Slide 25Slide 26Mobility: GSM versus Mobile IPWireless, mobility: impact on higher layer protocolsChapter 6 summaryWireless, Mobile Networks6-1Chapter 6 outline6.1 Introduction Wireless6.2 Wireless links, characteristicsCDMA6.3 IEEE 802.11 wireless LANs (“Wi-Fi”)6.4 Cellular Internet Accessarchitecturestandards (e.g., GSM)Mobility6.5 Principles: addressing and routing to mobile users6.6 Mobile IP6.7 Handling mobility in cellular networks6.8 Mobility and higher-layer protocols6.9 SummaryWireless, Mobile Networks6-2What is mobility?spectrum of mobility, from the network perspective:no mobilityhigh mobilitymobile wireless user, using same access pointmobile user, passing through multiple access point while maintaining ongoing connections (like cell phone)mobile user, connecting/ disconnecting from network using DHCP.wide area networkWireless, Mobile Networks6-3Mobility: vocabularyhome network: permanent “home” of mobile(e.g., 128.119.40/24)permanent address: address in home network, can always be used to reach mobilee.g., 128.119.40.186home agent: entity that will perform mobility functions on behalf of mobile, when mobile is remoteWireless, Mobile Networks6-4Mobility: more vocabularywide area networkcare-of-address: address in visited network.(e.g., 79,129.13.2) visited network: network in which mobile currently resides (e.g., 79.129.13/24)permanent address: remains constant (e.g., 128.119.40.186)foreign agent: entity in visited network that performs mobility functions on behalf of mobile. correspondent: wants to communicate with mobileWireless, Mobile Networks6-5How do you contact a mobile friend:search all phone books?call her parents?expect her to let you know where he/she is?I wonder where Alice moved to?Consider friend frequently changing addresses, how do you find her?Wireless, Mobile Networks6-6Mobility: approacheslet routing handle it: routers advertise permanent address of mobile-nodes-in-residence via usual routing table exchange.routing tables indicate where each mobile locatedno changes to end-systemslet end-systems handle it: indirect routing: communication from correspondent to mobile goes through home agent, then forwarded to remotedirect routing: correspondent gets foreign address of mobile, sends directly to mobileWireless, Mobile Networks6-7let routing handle it: routers advertise permanent address of mobile-nodes-in-residence via usual routing table exchange.routing tables indicate where each mobile locatedno changes to end-systemslet end-systems handle it: indirect routing: communication from correspondent to mobile goes through home agent, then forwarded to remotedirect routing: correspondent gets foreign address of mobile, sends directly to mobilenot scalable to millions of mobilesMobility: approacheswide area networkWireless, Mobile Networks6-8Mobility: registrationend result:foreign agent knows about mobilehome agent knows location of mobilehome networkvisited network1mobile contacts foreign agent on entering visited network2foreign agent contacts home agent home: “this mobile is resident in my network”Wireless, Mobile Networks6-9Mobility via indirect routingwide area networkhomenetworkvisitednetwork3241correspondent addresses packets using home address of mobilehome agent intercepts packets, forwards to foreign agentforeign agent receives packets, forwards to mobilemobile replies directly to correspondentWireless, Mobile Networks6-10Indirect Routing: commentsmobile uses two addresses:permanent address: used by correspondent (hence mobile location is transparent to correspondent)care-of-address: used by home agent to forward datagrams to mobileforeign agent functions may be done by mobile itselftriangle routing: correspondent-home-network-mobileinefficient when correspondent, mobile are in same networkWireless, Mobile Networks6-11Indirect routing: moving between networkssuppose mobile user moves to another networkregisters with new foreign agentnew foreign agent registers with home agenthome agent update care-of-address for mobilepackets continue to be forwarded to mobile (but with new care-of-address)mobility, changing foreign networks transparent: on going connections can be maintained!1234Wireless, Mobile Networks6-12Mobility via direct routinghomenetworkvisitednetworkcorrespondent requests, receives foreign address of mobilecorrespondent forwards to foreign agentforeign agent receives packets, forwards to mobilemobile replies directly to correspondentWireless, Mobile Networks6-13Mobility via direct routing: commentsovercome triangle routing problemnon-transparent to correspondent: correspondent must get care-of-address from home agentwhat if mobile changes visited network?1234Wireless, Mobile Networks6-14wide area network1foreign net visited at session startanchorforeignagent24new foreignagent3correspondentagentcorrespondentnew foreignnetworkAccommodating mobility with direct routinganchor foreign agent: FA in first visited networkdata always routed first to anchor FAwhen mobile moves: new FA arranges to have data forwarded from old FA (chaining)5Wireless, Mobile Networks6-15Chapter 6 outline6.1 Introduction Wireless6.2 Wireless links, characteristicsCDMA6.3 IEEE 802.11 wireless LANs (“Wi-Fi”)6.4 Cellular Internet Accessarchitecturestandards (e.g., GSM)Mobility6.5 Principles: addressing and routing to mobile users6.6 Mobile IP6.7 Handling mobility in cellular networks6.8 Mobility and higher-layer protocols6.9 SummaryWireless, Mobile Networks6-16Mobile IPRFC 3344has many features we’ve seen: home agents, foreign agents, foreign-agent registration, care-of-addresses, encapsulation (packet-within-a-packet)three components to standard:indirect routing of datagramsagent discoveryregistration with home agentWireless, Mobile Networks6-17Mobile IP:
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