Macro/micro-mobility fast handover in hierarchical mobile IPv6

Abstract

Mobile Internet Protocol version 6 (MIPv6) has been proposed to solve the problem of mobility in the new era of Internet by handling routing of IPv6 packets to mobile nodes that have moved away from their home network. Users will move frequently between networks, as they stay connected to the Internet. Thus, as mobility increases across networks, handovers will significantly impact the quality of the connection and user application.

However, MIPv6 only defines means of managing global (macro)-mobility but does not address micro-mobility separately. Instead, it uses the same mechanism in both cases. This involves long handover delay and signaling load. The Hierarchical Mobile IPv6 (HMIPv6) protocol has been proposed as an extension of basic MIPv6 to solve this problem by splitting the handover management into macro-mobility and micro-mobility schemes. HMIPv6 introduced a new protocol agent called Mobility Anchor Point (MAP) to manage mobility and serve as a local entity to aid in mobile handover. The handover (or registration) operation is the operation when MN registers its presence to its Home Agent (HA) and Correspondent Node (CN).

This paper proposes a mechanism to perform fast handover in HMIPv6 by adopting the multicast technique to the MAP for both macro-mobility and micro-mobility management. Our proposal is designed to minimize service disruption that occurs during the registration operation. We simulate the performance using network simulator (NS-2) and we present and analyze the performance testing for our proposal by comparing it with the basic hierarchical mobile IPv6. The results show that our scheme allows the MN to receive packets faster than the basic HMIPv6.

Introduction

There has recently been almost universal recognition that Mobile IP [1], the current standard for IP-based mobility management, needs to be enhanced to meet the needs of future cellular environment. Mobile IP supports user mobility in the network layer that allows mobile IP to be transparent to other layers. However, Mobile IP has several drawbacks. IETF introduced Mobile IPv6 as the successor of Mobile IPv4 and every drawback in Mobile IPv4 are solved in Mobile IPv6 [2]. Although Mobile IPv6 supports mobility, several mobility requirements have not been achieved. The list of main requirements specific to an IP-based mobility management protocol are as follows [3]:

• Hierarchical structure—to localize scope of location updates,

• Support seamless Handover—Packet redirection with minimal delay, and

• Provides compatibility with QoS such as support for real time applications

Mobile IPv6 faces some problems due to its handover management. The problems occurs when a mobile node moves from one access point to another access point in a small coverage area (micro-mobility), which reduces frequent handover, such that MIPv6 will not be suitable for such scenario under that circumstances. MIPv6 generates significant amount of signaling traffic in the core network, even for local movement, followed by long interruption during the handover.

Hierarchical Mobile IPv6 (HMIPv6) [4] proposed as an extension to the basic Mobile IPv6 in order to solve these problems in mobile IPv6. It does this by splitting the mobility management into macro- and micro-mobility. Even though it may reduce the handover delay and overhead in term of bytes or packets but it still suffers from long delays.

In this paper we describe a modification to hierarchical mobile IPv6 to support fast handover by adopting the multicast mechanism in HMIPv6 protocol. The remainder of this paper is organized as follows: Firstly, the nature of the problems pertinent in Mobile IPv6 is discussed. Secondly, a brief review of Mobile IPv6 and HMIPv6 is presented. Thirdly, a description of our proposed solution for HMIPv6 macro/micro-mobility management is introduced. Fourthly, simulation results and performance testing is presented. And finally the paper is concluded in Section 5.