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1、Mobile IPv6 Ad hoc Gateway with Handover Optimization指導老師：黃培壝 老師 學生：藍成浩OutlinenINTRODUCTIONnNETWORK REQUIREMENTS Mobile IPv6 Infrastructure Ad hoc On-demand Distance Vector Routing (AODVv6)nMOBILE IPV6 AD HOC GATEWAY System Architecture Mobile IPv6 Extensions AODVv6 Extensions Gateway DiscoverynHAND
2、OVER OPTIMIZATIONnEXPERIMENTS AND RESULTSnCONCLUSION AND FUTURE WORKIntroductionnFuture wireless networks will be available in every mobile environment, especially in vehicles like busses, cars, trains, and airplanes.nThese networks will provide wireless access to the Internet so that mobile users a
3、re able to use IP-based networks for exchanging data or downloading emails. IntroductionnSuch networks use ad hoc communication via multihop ad hoc nodes.nHence, future mobile devices will have a combination of multiple wireless interfaces and multihop ad hoc support.MNMNIntroductionMobile IPv6 Ad h
4、oc GatewayInternet networkMobile usersOne mobile scenario in the future is a wireless ad hoc network in a train which supports wireless Internet access for all mobile ad hoc users in every cabin.IntroductionnFor this mobility scenario the gateway has to be mobile to support vertical handovers betwee
5、n different bearer systems and it has to provide horizontal handovers.nVertical handovers should be forced when the WLAN link quality is not sufficient or the network congestion decreases the throughput.IntroductionnMobile IPv6 provides handovers between different bearer systems and allows transpare
6、nt mobility support in heterogeneous network environments.nIt uses so-called movement detection to detect new access networks and exchanges binding updates (BU) between the mobile node and the Home Agent.IntroductionnFor high velocities this movement detection is not efficient and leads to high pack
7、et loss.nHence, in this study an optimization for vertical handovers between different bearer systems .IntroductionnThis paper describes the advantages of IPv6 mobility , especially the integration of Mobile IPv6 together with the ad hoc routing protocol AODVv6 nThe vertical handover optimization is
8、 described in this paper which is based on a proactive handover decision using the link quality of the WLAN access point to decide when a handover has to be forced.Mobile IPv6 InfrastructureMobile IPv6 Ad hoc GatewayMobile IPv6 InfrastructurenThe Mobile IPv6 infrastructure that is shown in Fig.1 pro
9、vides access to a WLAN system and a cellular network.nTherefore, a WLAN access point (802.11b) is attached via Access Router (AR) with the HA and provides fully IPv6 access to the MN.Mobile IPv6 InfrastructurenGPRS/UMTS where the infrastructure of the mobile operator is mainly based on IPv4.nTunnell
10、ing mechanismsnOpen VPN was used in this study to tunnel the IPv6 traffic between the MN and the HA through the IPv4 network of the mobile operator transparently.Ad hoc On-demand Distance Vector Routing (AODVv6)nReactive routing protocol.Route discoveryAd hoc On-demand Distance Vector Routing (AODVv
11、6)Route discoveryAd hoc On-demand Distance Vector Routing (AODVv6)Route discoveryAd hoc On-demand Distance Vector Routing (AODVv6)nRoute maintenance : hello message 、 RERRnA route error (RERR) message is sent by intermediate nodes when a route is not valid anymore.nAfter the source node receives a R
12、ERR the node starts the route discovery again to find a valid route to the destination.System ArchitectureSystem ArchitecturenThe gateway contains the Mobile IP stack that is required to implement global mobility of the gateway .nTo integrate the ad hoc network the gateway also contains the AODVv6 s
13、tack to attach the ad hoc network to the mobile gateway.nAt last the system architecture also contains the handover optimization to reduce the packet loss during handovers.Mobile IPv6 ExtensionsnFrom the Mobile IP point of view the MN is the endpoint of an active communication link that means that t
14、he MN does not include any rerouting options for attached networks.nTherefore, it is required to extend the routing behaviour of the MN.Mobile IPv6 ExtensionsnThe kernel of the MN has to be extended to retransmit data packets from/to the attached ad hoc network and to receive the agent advertisement
15、s simultaneously.nHence, the forwarding flag at the default MNs interface has to be activated and the accept_rf flag has to be adapted to provide the gateway support.Mobile IPv6 ExtensionsnMoreover, the Home Agent does not maintain any route to the ad hoc network .nIt is also required to extend the
16、Home Agent functions to support routing information of the attached ad hoc network after each binding update.AODVv6 ExtensionsnThe AODVv6 implementation which was used for this study only provides local reachability.nHowever, the integration of an attached ad hoc network requires the support of global routable IPv6 addresses.Gateway DiscoverynThe AODVv6 implementation in 7 does not contain any gateway discovery.nThis extension allows ad hoc nodes to find the mobile gateway and to establish a
