Abstract

Although a lot of progress has been made in recent years, supporting mobility in the Internet is still a difficult challenge. The Internet today consists of multiple networks, interconnected by IP routers. In each network multiple subnetworks may coexist, also connected via routers. One subnetwork may connect multiple LAN segments by means of MAC switches. For scalability purposes, IP addresses are hierarchical, which allows routing decisions to be performed using address aggregates. Due to this addressing structure, the IP address of a mobile user needs to change dynamically as the user moves from one subnetwork to another (or one network to another) to match addressing at the new subnet (or the new network). Unlike IP addresses, MAC addresses are flat, as the scale of the problem is smaller. Switches inside a subnetwork track individual users and forward packets to them.

If a source sends packets to a destination that is moving and changing IP addresses, the contents of the packet may refer to a destination address that is stale, and the packet may be discarded, or redirected by some special-purpose entity in the network known as an agent. The source may be informed of the change in the IP address of the destination as well, so that future packets can be sent directly to its new location. As users move inside a subnetwork, changes need to take place at one or more switches tracking that user, in an attempt to maintain connectivity to the user at all times.

Tracking updates may take a long time to arrive at the agents, end-hosts and switches, which can result in a temporary loss of connectivity to the user. This becomes particularly noticeable when users are engaged in streaming multimedia applications, and may even result in the abortion of TCP sessions. Furthermore, current technologies significantly limit the number of individual addresses that can be tracked by a device built at a reasonable cost. Therefore, any solution to support mobility must deal with inherent delays caused by distances between the moving user and entities in the network that track and assist the user, as well as limitations of the current technology in terms of cost and performance.

In this paper we assess, design and optimize schemes to support mobility in the Internet. These schemes exploit techniques called address-lookahead, packet n-casting, transparent learning and light-weight explicit registration. Via numerical simulation, we demonstrate considerable improvements in the user-perceived quality of applications, at no significant increase in cost. For example, 40% more voice calls can experience a high level of quality, at the cost of only a 3% increase in the bandwidth consumption in the Internet.

Article Outline

1. Introduction

1.1. Macro-mobility support

1.2. Micro-mobility support

1.3. Macro-mobility support using a micro-mobility infrastructure

2. Assessing the impact of handover delay

2.1. Introduction

2.2. Related work

2.2.1. The mobile IP scheme

2.2.2. End-to-end schemes

2.3. Proposed work

2.4. Experiments

2.4.1. Simulation description

2.4.2. Results

2.4.2.1. TCP/IP application

2.4.2.2. Voice application

2.4.2.3. Bi-cast overhead

2.5. Conclusions

3. Optimizing user tracking in LAN-based MANs

3.1. Introduction

3.2. Related work

3.3. Schemes

3.3.1. FLOOD

3.3.2. SNOOP

3.3.3. SNOOP_PU

3.3.3.1. General description

3.3.3.2. Our implementation

3.3.4. REG

3.3.4.1. General description

3.3.4.2. Our implementation

3.3.5. REG_SNOOP

3.4. Experiments

3.5. Results

3.5.1. Packet amplification

3.5.2. Packet loss

3.5.3. Average database size

3.5.4. Comparing the schemes

3.5.5. Network tuning

4. Exploiting Mobilane to optimize macro-mobility support

4.1. Basic idea

4.2. Comparing the macro-mobility schemes

5. Conclusions

References

Vitae

Corresponding author