We propose a distributed architecture of Web filtering system focused on its operation and implementation for IPv6 home networks. The realized system, called WKeeper, employs the feature of IPv6 anycast to achieve distributed load balance. WKeeper has been proven to be functioning well in both IPv4 and IPv6 networks even with mobility support. In a home network environment, WKeeper efficiently and precisely maintains the URL-block-list database with enormous amount of entries, as well as its operation is robust and with low cost. Besides, experimental result shows that the delay of query response is bounded significantly even if heavy load.

As WDM-based optical networks are becoming the right choice for the next-generation Internet networks to transport high-speed IP traffic, the leading role of wireless ATM (WATM) networks will be undoubtedly replaced with wireless WDM (WWDM) networks for providing high quality of services to mobile users. Meanwhile, multicasting has played an increasingly important role in many conventional and emerging applications, such as teleconferencing and distributed games. In this paper, a constrained optical tree migration scheme (COTMS) is proposed to support multicast services in WWDM networks. COTMS is an enhancement of our previous work, called CTMS, for adapting to the characteristic of WDM-based backbone networks. CTMS can properly deal with the constrained tree migration problem for generic wireless networks, and COTMS inherits the efficiencies of CTMS entirely. Simulation results show that COTMS can markedly reduce the resources used per multicast tree, thus achieving both low handoff-dropping/join-blocking rate and high resource utilization. More importantly, we demonstrate how COTMS incorporating crossover optical switch discovery can be used to support real-time traffic for heterogeneous (i.e., unicast and multicast) connections in a uniform and unified manner. The proposed scheme is also suitable for routing over fully mobile (ad hoc) networks in which multiple frequencies are used for data communications.

This study considers the multicasting problem over mobile wireless systems in the context of generic wireless systems. Specifically, a novel constrained tree migration scheme (CTMS) is created to support multicast services in mobile wireless networks. The salient features of the novel CTMS include: (1) automatically recognizing the inefficiency of the multicast trees, then migrating them to better ones, while maintaining the QoS guarantees specified by mobile users; (2) conserving network resources by maintaining a low-cost multicast tree, thus accommodating more users; (3) operating efficiently in a truly distributed manner through event driven and diffusing computations, thus increasing the degree of scalability; (4) synchronizing data transmission flow for transparency during the tree migration, and thus providing seamless handoff control. Finally, the novel CTMS also handles the concurrent migration problem effectively within the wireless system, thus eliminating the oscillation paradox. Extensive simulation results show that CTMS can significantly reduce the resources used per multicast tree, thus achieving both low handoff-dropping/join-blocking rate and high resource utilization.

Wireless personal communications will be provided via the usage of microcells in urban areas. The current centralized architecture may be unsuitable with the increased processing load and handoff rate associated with microcells. Some distributed architectures based upon interconnected IEEE 802.6 MAN'S for wireless personal communications have been proposed recently. The IEEE 802.6 MAN is attractive since it also provides isochronous services which are quite suitable for voice communications. In such a network, a communication path between two mobile terminals may be inefficient due to the lack of better paths when the path is established or become inefficient due to the mobility of terminals, e.g., the path elongates and consumes too much isochronous channels. In this paper, a distributed paths migration scheme is proposed for the IEEE 802.6 based personal communication networks. This distributed scheme automatically recognizes inefficient paths and migrates them to better ones, if any. During the migration, the property of isochronous services is also preserved. The performance of this scheme is evaluated by simulations. Simulation results show that the proposed paths migration scheme dramatically reduces the number of isochronous channels consumed per path. As a result, the call blocking rate is reduced and the number of successful established paths is increased significantly.>