A Study Of IPv6Tunneling Transition Architecture And Protocols In Access Networks

With the exhaustion of IPv4address space, IPv6is widely believed to replace IPv4for Internet development. Due to the incompatibility between IPv4and IPv6protocols,IPv4and IPv6networks cannot communicate directly. Therefore the transition from IPv4to IPv6has become a task of great significance and urgency. The access networks face thehuge numbers of network users and upper layer applications directly, as well as consumemassive addresses, which makes the transition of access networks the essential difcultyfor IPv6transition. The dissertation investigates the problem of IPv4-IPv6coexistence&transition in access networks comprehensively, and develops solutions in mechanism&protocols, address resource utilization method and placement&routing plan for accessnetwork transition. The contributions of this dissertation include the following aspects:1.Survey the research works in the field, especially the mainstream transition mech-anisms. The dissertation states the basic problem of IPv6transition and the principleof translation&tunneling techniques, analyzes the mainstream transition mechanismsraised so far in IETF, summarizes the feasible mechanisms among them based on theirapplication scenarios, and concludes the difculties and the trend of the study in the field.2.Propose the IPv6tunneling transition architecture for access networks. The disser-tation formalizes the basic transition problem of heterogeneous end-to-end connectivity,proposes the methods of building dual-stack network layer connectivity and end-to-endpath using tunneling technique, designs a homogeneous end-to-end communication mod-el. The IPv6tunneling transition architecture avoids cross-protocol inter-connection, andachieves the advantages on end-to-end transparency and scalability. Based on that, thebasic form of access network transition is determined as single-stack network plus hub&spoke tunnel. The follow-up roadmap of this dissertation is determined as well, tostudy the elements of tunneling mechanism, address resource allocation and heteroge-neous routing for access network transition.3.Develop the4over6tunneling access mechanisms and their supporting protocols.The dissertation analyzes the flaws in the existing IPv4-over-IPv6access mechanisms,designs the protocols to allocate IPv4addresses in IPv6network and to enable port-set-style address sharing, and then develops the Public4over6and Lightweight4over6tun-neling access mechanisms. The mechanisms have the merits of end-to-end transparency, IPv4-IPv6address independency and lightweight state maintenance.4.Propose an efcient algorithm to allocate address resources in port-set granular-ity. To solve the heterogeneous address resource allocation and sharing problem in ac-cess network, the dissertation builds a resource allocation model for port-set-granularityresources, and develops an algorithm which organizes, allocates and recycles the trans-formable port-set units neatly. The algorithm achieves sufcient utilization of the addressspace in efcient execution time. An enhanced algorithm which further explores the timeinformation of the units is proposed to improve the address utilization rate.5.Develop a low-cost strategy for concentrator placement and route planning of tun-neling access mechanisms. To plan the tunneling mechanisms in access network in con-sideration of the hub concentrating feature, the dissertation builds an optimization mod-el for concentrator placement and route planning, and proposes a solution which com-bines the methods of variable decomposition, topology transformation and minimum-interference routing, to find the positions for the concentrators and the forwarding pathsfor the tunneling flows. The solution produces a deployment plan for the tunneling accessmechanisms with a low transmission cost.