Abstract-High-end networking applications such as Internet TV and software distribution have generated a demand for multicast protocols to be an integral part of the network. This will allow such applications to support data dissemination to large groups of users in a scalable and reliable manner. Existing IP multicast protocols lack these features and also require state storage in the core of the network which can be costly to implement.In this paper, we present a new multicast protocol referred to as MENU. MENU realises a scalable and a reliable multicast protocol model by pushing the tree building complexity to the edges of the network, thereby eliminating processing and state storage in the core of the network. The MENU protocol builds multicast support in the network using mobile agent based Active Network services -Netlets, and unicast addresses. The multicast delivery tree in MENU is a two level hierarchical structure where users are partitioned into client communities based on geographical proximity. Each client community in the network is treated as a single virtual destination for traffic from the server. Netlet based services referred to as Hot Spot Delegates (HSDs) are deployed by servers at "hot spots" close to each client community. They function as virtual traffic destinations for the traffic from the server and also act as virtual source nodes for all users in the community. The source node feeds data to these distributed HSDs which in turn forward data to all downstream users through a locally constructed traffic delivery tree. It is shown through simulations that the resulting system provides an efficient means to incrementally build a source customisable secured multicast protocol which is both scalable and reliable. Furthermore, results show that MENU employs minimal processing and reduced state information in networks when compared to existing IP multicast protocols.

Abstract-High-end networking applications such as ecommerce, multimedia, distributed data analysis and advanced collaborative environments feature demanding end-to-end quality of service (QoS) requirements. Due to the heterogeneity exhibited by the Internet, a route from source to destination for such a flow may not be available which is comprised exclusively of QoS supporting path segments. Hence the flow must traverse one or more non-QoS path segments referred to here as reservation gaps. In this paper we study the problem of reservation gaps and their impact on QoS and present a solution to address the deficiencies caused by such gaps, using an Active Network approach based on the mobile agent paradigm. Furthermore, to improve the reliability in path selection and to minimise the influence of reservation gaps along the path of a QoS flow, we propose two routing algorithms, the most reliable -shortest path (MR-S) algorithm and the shortest -most reliable path (S-MR) algorithm, that select paths with the minimum number of reservation gaps. The Active Network based solution we propose works autonomously and scales to large networks such as the Internet. We demonstrate the advantages of such a solution using simulations which compares operational characteristics of QoS flows when traversing non-managed and actively managed reservation gaps. We also demonstrate the benefits of employing a routing algorithm such as MR-S or S-MR that accounts for reservation gaps in place of conventional Shortest-Path routing algorithms.

This paper describes a method for providing QoS support to legacy (non-QoS aware) network applications. This facility allows such applications to request desired QoS levels from QoS supporting networks and thus helps to increase their lifespan and performance levels. We use mobile-agent components called Netlets for this purpose. Netlets are nomadic components that roam in a network providing predefined network services. The solution we propose is not restricted to any particular QoS model or signalling protocol, and thus can readily accommodate emerging networking standards. This approach to QoS support, by decoupling applications from the specifics of network QoS support, which may differ among networks, or evolve over time, should greatly facilitate the introduction of new real-time services.

Abstract-Replication of web content in the Internet has been found to improve service response time, performance and reliability offered by web services. When working with such distributed server systems, the location of servers with respect to client nodes is found to affect service response time perceived by clients in addition to server load conditions. This is due to the characteristics of the network path segments through which client requests get routed. Hence, a number of researchers have advocated making server selection decisions at the client-side of the network. In this paper, we present a transparent approach for clientside server selection in the Internet using Netlet services. Netlets are autonomous, nomadic mobile software components which persist and roam in the network independently, providing predefined network services. In this application, Netlet based services embedded with intelligence to support server selection are deployed by servers close to potential client communities to setup dynamic service decision points within the network. An anycast address is used to identify available distributed decision points in the network. Each service decision point transparently directs client requests to the best performing server based on its in-built intelligence supported by real-time measurements from probes sent by the Netlet to each server. It is shown that the resulting system provides a client-side server selection solution which is server-customisable, scalable and fault transparent.