Mobile IPv6 Ad hoc Gateway with Handover Optimization

1. Mobile IPv6 Ad hoc Gateway with Handover Optimization 指導老師：黃培壝 老師 學生：藍成浩

2. Outline • INTRODUCTION • NETWORK REQUIREMENTS Mobile IPv6 Infrastructure Ad hoc On-demand Distance Vector Routing (AODVv6) • MOBILE IPV6 AD HOC GATEWAY System Architecture Mobile IPv6 Extensions AODVv6 Extensions Gateway Discovery • HANDOVER OPTIMIZATION • EXPERIMENTSANDRESULTS • CONCLUSION AND FUTURE WORK

3. Introduction • Future wireless networks will be available in every mobile environment, especially in vehicles like busses, cars, trains, and airplanes. • These networks will provide wireless access to the Internet so that mobile users are able to use IP-based networks for exchanging data or downloading emails.

4. Introduction • Such networks use ad hoc communication via multihop ad hoc nodes. • Hence, future mobile devices will have a combination of multiple wireless interfaces and multihop ad hoc support. MN MN

5. Introduction One 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. Internet network Mobile IPv6 Ad hoc Gateway Mobile users

6. Introduction • For this mobility scenario the gateway has to be mobile to support vertical handovers between different bearer systems and it has to provide horizontal handovers. • Vertical handovers should be forced when the WLAN link quality is not sufficient or the network congestion decreases the throughput.

7. Introduction • Mobile IPv6 provides handovers between different bearer systems and allows transparent mobility support in heterogeneous network environments. • It uses so-called movement detection to detect new access networks and exchanges binding updates (BU) between the mobile node and the Home Agent.

8. Introduction • For high velocities this movement detection is not efficient and leads to high packet loss. • Hence, in this study an optimization for vertical handovers between different bearer systems .

9. Introduction • This paper describes the advantages of IPv6 mobility , especially the integration of Mobile IPv6 together with the ad hoc routing protocol AODVv6 • The vertical handover optimization is 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.

10. Mobile IPv6 Infrastructure Mobile IPv6 Ad hoc Gateway

11. Mobile IPv6 Infrastructure • The Mobile IPv6 infrastructure that is shown in Fig.1 provides access to a WLAN system and a cellular network. • Therefore, a WLAN access point (802.11b) is attached via Access Router (AR) with the HA and provides fully IPv6 access to the MN.

12. Mobile IPv6 Infrastructure • GPRS/UMTS where the infrastructure of the mobile operator is mainly based on IPv4. • Tunnelling mechanisms • Open 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.

13. Ad hoc On-demand Distance Vector Routing (AODVv6) • Reactive routing protocol. Route discovery

14. Ad hoc On-demand Distance Vector Routing (AODVv6) Route discovery

15. Ad hoc On-demand Distance Vector Routing (AODVv6) Route discovery

16. Ad hoc On-demand Distance Vector Routing (AODVv6) • Route maintenance : hello message 、 RERR • A route error (RERR) message is sent by intermediate nodes when a route is not valid anymore. • After the source node receives a RERR the node starts the route discovery again to find a valid route to the destination.

17. System Architecture

18. System Architecture • The gateway contains the Mobile IP stack that is required to implement global mobility of the gateway . • To integrate the ad hoc network the gateway also contains the AODVv6 stack to attach the ad hoc network to the mobile gateway. • At last the system architecture also contains the handover optimization to reduce the packet loss during handovers.

19. Mobile IPv6 Extensions • From the Mobile IP point of view the MN is the endpoint of an active communication link that means that the MN does not include any rerouting options for attached networks. • Therefore, it is required to extend the routing behaviour of the MN.

20. Mobile IPv6 Extensions • The kernel of the MN has to be extended to retransmit data packets from/to the attached ad hoc network and to receive the agent advertisements simultaneously. • Hence, the forwarding flagat the default MN’s interface has to be activated and the accept_rf flaghas to be adapted to provide the gateway support.

21. Mobile IPv6 Extensions • Moreover, the Home Agent does not maintain any route to the ad hoc network . • It is also required to extend the Home Agent functions to support routing information of the attached ad hoc network after each binding update.

22. AODVv6 Extensions • The AODVv6 implementation which was used for this study only provides local reachability. • However, the integration of an attached ad hoc network requires the support of global routable IPv6 addresses.

23. Gateway Discovery • The AODVv6 implementation in [7] does not contain any gateway discovery. • This extension allows ad hoc nodes to find the mobile gateway and to establish a connection to the Internet.

24. HANDOVER OPTIMIZATION • The Mobile IPv6 Ad hoc Gateway supports an optimization for vertical handovers to reduce packet loss. • This allows seamless mobility but it leads to packet loss during the handover, because there is a short time period where the previous access link is lost.

25. HANDOVER OPTIMIZATION • Proactive handover decision . • The proactive handover decision is based on receiving link layer information to decide when a handover has to be forced [9] and is part of the POLIMAND (Policy based Mobile IPv6 Handover Decision) definition that is described in [10]. • POLIMAND defines a threshold which indicates the link quality so that a handover to a reliable bearer system can be forced.

26. EXPERIMENTS AND RESULTS • The Mobile IPv6 infrastructure consists of one HA that is linked to a WLAN AP. • The HA is connected to a CN that is also located within the test bed and is connected to the Internet. • A FR that is also located in the test bed is used to attach the MN over a GPRS link to the test bed.

27. EXPERIMENTS AND RESULTS • An OpenVPN tunnel at the FR is used for transparent IPv6 connectivity between HA and MN. • Mandrake Linux OS and Kernel 2.4.22. • All Mobility Agents are equipped with a Linux IPv6 Router Advertisement Daemon [11] to broadcast the required agent advertisements.

28. EXPERIMENTS AND RESULTS • The handover of the mobile gateway are controlled by an attenuator to reduce the link quality between the WLAN AP and the WLAN card of the mobile gateway. • To define the link layer threshold 5 iterations were measured.

29. EXPERIMENTS AND RESULTS • During the iteration 200 ICMP packets were sent between the MN and the CN with a packet size of 64 bytes per second. • To measure the mobility of the gateway 10 iterations were taken to examine the packet loss during vertical handovers between WLAN and GPRS.

30. EXPERIMENTS AND RESULTS • The threshold for the link quality is derived from the measured link quality of the WLAN access point when the first packet is lost.

31. EXPERIMENTS AND RESULTS

32. EXPERIMENTS AND RESULTS • The results of vertical handovers were measured during an increasing number of handovers using a constant advertisement period (1 advertisement per second)

33. EXPERIMENTS AND RESULTS

34. CONCLUSION AND FUTURE WORK • The interconnection of ad hoc networks and the Internet can be achieved by a mobile gateway that was presented in this study. • This gateway has to be mobile to provide mobility support of entire ad hoc networks that will be located in several vehicles in the future.

35. CONCLUSION AND FUTURE WORK • Fulfil the QoS requirements in mobile ad hoc network.