Mobile Computing
Mobile IPv6

Mobile IPv6 (MIPv6) is a protocol developed as a subset of Internet Protocol version 6 (IPv6) to support mobile connections. MIPv6 is an update of the IETF (Internet Engineering Task Force) Mobile IP standard (RFC 2002) designed to authenticate mobile devices (known as mobile nodes) using IPv6 addresses. In traditional IP routing, IP addresses represent a topology. Routing mechanisms rely on the assumption that each network node will always have the same point of attachment to the Internet, and that each node's IP address identifies the network link where it is connected. In this routing scheme, if you disconnect a mobile device from the Internet and want to reconnect through a different network, you have to configure the device with a new IP address, and the appropriate netmask and default router. Otherwise, routing protocols have no means of delivering datagrams (packets), because the device's network address doesn't contain the necessary information about the node's network point of attachment to the Internet. MIPv6 allows a mobile node to transparently maintain connections while moving from one subnet to another. Each device is identified by its home address although it may be connecting to through another network. When connecting through a foreign network, a mobile device sends its location information to a home agent, which intercepts packets intended for the device and tunnels them to the current location. Concerning MIPv6 protocol, an MN can determine its network layer movement by using Router Discovery and Neighbor Unreachability Detection. After a MN makes a new Care of Address (CoA), it must check its uniqueness by DAD.

The delay of network layer-based movement detection, non-optimized time sequencing of handover procedures and latency in configuring a new care of address are inevitable in Mobile IPv6. These delays will cause packet disruption and increase network load. But Fast handovers for Mobile IPv6 could be reduced for real time applications and throughput sensitive application by fast movement detection scheme with L2 trigger event. Actually, the handover latency could be too long regarding real time multimedia applications.

One of the major areas of research taking place at the LIST lab deals with the solutions to reduce handover latency in MIPv6 networks. We propose an Efficient Movement Detection procedure which quickly sends Router Solicitation (RS) and Router Advertisement (RA) message without Random Delay using Stored RA messages with unicast. Doing so quickly determines the uniqueness of a new CoA using the modified Neighbor cache of an access router. In particular, we focus on the delay optimization of movement detection and DAD for fast handover in Mobile IPv6 Networks. In movement detection, RS delays the transmission for a random amount of time (Random delay for RS, RD_RS) [6]. This time serves to alleviate congestion when many hosts start up on a link at the same time, which might happen after recovery from a power failure. Also, RA must be delayed by a random amount time (Random delay for RA, RD_RA). This time is required to prevent multiple nodes from transmitting at exactly the same time, and to prevent long-range periodic transmissions from synchronizing with each other. These random delays are the second largest delay after DAD in MIPv6 Network-Layer handovers. In DAD procedure, after generation of a CoA, an MN should perform DAD for testing the new CoA’s uniqueness within the new link. The proposed scheme enhances processing time of DAD using lookup algorithm.

Figure 1 shows the standard Mobile IPv6 Architecture.

Fig. 1. Standard MIPv6 Environment

Figure 2 shows the standard Mobile IPv6 handover procedure which cause long time handover delay.

Fig. 2. Standard MIPv6 Handover Procedure

Fig. 3. Enhanced MIPv6 with Fast Movement Detection and DAD


Other Resources:

[1] Byungjoo Park, In Huh, Haniph A. Latchman, “An Approach to Efficient and Reliable Media Streaming Scheme in Mobile IPv6 Networks”, in Proc. IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (ISBMSB’06), April 6-7, 2006.

[2] Byungjoo Park, Sunguk Lee, Haniph A. Latchman, “Performance Analysis of Enhanced-Mobile IPv6 with Fast Handover over End-to-End TCP”, in Proc. the IEEE Wireless Communications and Networking Conference (WCNC’06), April 3-6, 2006.

[3] Byungjoo Park, Haniph A. Latchman, “Fast Handover Scheme Based on Enhanced Access Point (EAP) for Mobile IPv6”, in Proc. IEEE International Conference on Advanced Communication Technology, Feb. 20-22, 2006, pp. 759-763.