تجزیه و تحلیل عملکرد از طرح تحرک دامنه مجازی در مقابل پروتکل تحرک IPv6

The population of mobile users seeking connectivity to the Internet has been growing over the years, spurred by the capabilities of handsets and the increasing rich Internet content and services. Mobility management to enable efficient Internet access for users on the move is thus gaining significance. IETF has standardized several protocols such as Mobile IPv6, Hierarchical Mobile IPv6, and Proxy Mobile IPv6 to provide mobility management on the IP network. With future Internet design initiatives gaining momentum, it is important that these initiatives consider mobility management as an integral part of the design. In this article, we introduce the concept of Virtual Mobility Domain and describe the main features and key strengths of Virtual Mobility Domain that are designed to provide mobility management in a newly proposed tiered Internet architecture. Instead of IP addressing, the proposed Virtual Mobility Domain uses a tiered-addressing scheme to identify a mobile node with a single address regardless of its location. The tiered addressing provides a dynamic address length which brings less signaling overhead and scalable management. We also propose a collaborative network-based mobility management mechanism to provide low-latency handoffs and less processing-overhead on the mobile node compared to the IPv6-based protocols. The proposed mobility scheme unifies inter and intra-domain mobility management by introducing common anchor cloud concept which provides a distributed management and seamless mobility experience. We present comparative qualitative and quantitative performance analysis of Virtual Mobility Domain and aforementioned IPv6-based mobility protocols for Intra-AS roaming support. We examine handoff latency and signaling overhead performance of each protocol based on numerical results retrieved from analytical models and OPNET modeler based simulations. The results from a comparative performance study show the potential for more efficient mobility management under the proposed Internet architecture.

Significant advances in hardware and wireless technologies have made mobile communication devices affordable to a vast user community. With the advent of rich multimedia and social networking content, and influx of myriads of applications, there is an increasing user demand for Internet connectivity anywhere and anytime. Robust Internet protocols and evolutionary research efforts have enabled the Internet to withstand the demands of the users and the emerging technologies. Research programs worldwide such as the National Science Foundation’s Future Internet Design Initiative [1] and Future Internet Architecture Project [2] in the United States, the European Union’s sixth and seventh framework programs [3], the Asia consortium [4], and New Generation Networks [5] in Japan have started funding clean slate future Internet research to efficiently harness the related advanced technologies and to better address user demands. Mobility management is an integral feature in many of these future Internet designs [6]. Mobility management includes seamless roaming of mobile users requiring fast handoff with low latency and low packets loss to allow continuation of active sessions transparently as users change network connections [7]. The authors of this work proposed a tiered Internet architecture1 derived from the tiered structure existing today among Internet Service Providers (ISPs) to define their business and peering relationships [8] and [9]. The topological connections between ISPs exhibit a hybrid structure that leverages the attributes of hierarchical and distributed structures. In a tiered structure, there can be several entities in one tier such as an ISP, an Autonomous System (AS) or an access network that operate in a distributed and autonomous manner. However, entities at a lower tier are customers of entities at a higher tier, exhibiting a hierarchical relationship. The tiered structure enables defining Virtual Mobility Domains (VMDs) of varying scopes by deploying to any tier. VMD defines a virtual roaming boundary which is not geographically or physically constrained to a locality for a mobile user. A user is tracked with a single short-length tiered-address in the VMD. Seamless user movement within the domain is collaboratively managed by nodes in the network. Collaborative management scheme provides a distributed and scalable management of the mobility. In this article, extensive analytical and simulation based performance study of intra-AS roaming support of VMD [10] in a tiered Internet architecture in comparison with Mobile IPv6 (MIPv6) [11], Hierarchical Mobile IPv6 (HMIPv6) [12], and Proxy Mobile IPv6 (PMIPv6) [13] is presented. These protocols are chosen specifically because they present fundamentally different ways of handling a handoff and we aim to investigate the contributions due to locations and functions of the different mobility agents on the network. It is not possible to compare the VMD based mobility protocol with other recent future Internet solutions because most are in the research phase. However, a comparison with MIPv6, HMIPv6, and PMIPv6 will show the relative performance improvements achieved with VMD and also serve as benchmark for future mobility related studies. Our study in this paper reveal that VMD outperforms MIPv6, HMIPv6, and PMIPv6 significantly in terms of handoff latency, packet loss, and signaling overhead – the three important performance metrics to assess seamless user mobility. The rest of the paper is organized as follows. Section 2 covers a summary of previous and ongoing research on mobility management. Section 3 presents the tiered Internet architecture and the VMD concept, followed by VMD intra-AS roaming support in Section 4. The analytical models for VMD, MIPv6, HMIPv6, and PMIPv6 are provided in Section 5. Performance comparison of VMD against MIPv6, HMIPv6, and PMIPv6 based on both analytical and simulation models are presented in Section 6. Concluding remarks are given in Section 7.

In this article, we have presented a new mobility management protocol based on a Virtual Mobility Domain concept that is implemented in the proposed FCT internetworking model [8]. A VMD is defined as a virtual network cloud, which can be supported under a network cloud at an upper tier. MNs are given an address under the virtual network cloud to roam within the VMD. VMD supports network-based collaborative mobility management. A comparative analytical and simulation study of VMD is conducted with MIPv6, HMIPv6, and PMIPv6, as their specifications are available and this study is targeted as a benchmark for future comparative studies. Seamless roaming has been assessed based on handoff latency, packet loss, and signaling overhead during handoff. VMD manages intra-cloud handoff in 98.9%, 98.7%, and 28.5% less time compared to MIPv6, HMIPv6, and PMIPv6 respectively. VMD manages inter-cloud handoff in 98.7% and 98.2% less time compared to MIPv6 and HMIPv6, and in the same time as PMIPv6. In terms of signaling overhead for intra-cloud and inter-cloud handoffs respectively, VMD performs 90.3% and 80.6% better compared to MIPv6, 32.1% better and 35.7% worse compared to HMIPv6, and 62.5% and 25% better compared to PMIPv6. Collaborative mobility management helps VMD to perform better during intra-cloud handoffs as compared to inter-cloud handoffs while IPv6-based mobility protocols do not exhibit any improvement. The performance results show the potential for better seamless mobility management with new mobility management approaches that can be achieved with the new Internet architectures. The presented work has been limited to the introduction and performance improvements achieved by the VMD approach when deployed within an AS. Future work will include evaluation under inter-AS roaming scenarios and optimization based on the level of tiers supported under a VMD considering user requirements and quality of service.