Transparent and scalable client-side server selection using netlets

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 client-side 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

MENU: multicast emulation using netlets and unicast

High-end networking applications such as Internet TV and software distribution have generated a demand for multicast protocols as 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 is costly to implement. In this paper, we present a new multicast protocol referred to as MENU. It 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

Network support for multimedia applications using the Netlets architecture

Multi-party multimedia networking applications such as e-commerce, distributed data analysis, Internet TV and advanced collaborative environments feature stringent end-to-end Quality of Service (QoS) requirement and require globally distributed user groups to be interconnected. The variety of delivery requirements posed by such applications are best satisfied using highly customised networking protocols. Hence, a demand for networks to migrate from the current fixed service model to a more flexible architecture that accommodates a wide variety of networking services is emerging. New approaches are required in order to build such service oriented networks. Active networking is one such approach. Active networks treats the network as a programmable computation engine, which provides customised packet processing and forwarding operations for traffic flowing through network nodes. User applications can download new protocols into network elements at runtime, allowing rapid innovation of network services. This thesis makes the case for employing mobile agents to realise an active networking architecture, and describes such an architecture called the Netlets architecture. Netlets are autonomous, mobile components which persist and roam in the network independently, providing predefined network services. This thesis presents the design and implementation of the Netlet node and the service deployment m echanisms that are required to distribute Netlet services in the network. Using the Netlet toolkit, variety of network services were designed to provide network support for multimedia applications in the Internet. A service was implemented to enhance the working of the RSVP protocol in order to provide robust end-to-end QoS support even when the network is only partially QoS provisioned. A scalable and reliable multicast protocol was implemented using the unicast communication model that accommodate heterogeneous receiver terminals. Another service integrates client-side server selection support into web sessions established over the Internet. A service was also developed which provides QoS signalling support to legacy applications. It is shown that these Netlet services are of practical value using performance measurements to assess Netlet responsiveness. Netlet based solutions maybe deployed using existing technologies to provide support for a wide range of multimedia applications in the Internet. The Netlets architecture has thus been shown to allow value-added services to be added to existing networks. By optimising the Netlet architecture implementation, this may be extended to services operating on high-speed (1Gb/s and upwards) links. It thus shows promise as an architecture for building the next generation of active networking solutions

RSVP reservation gaps: problems and solutions

High-end networking applications such as e-commerce, 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 (MS-R) 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

MENU: Multicast Emulation using Netlets and Unicast

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. I

Stigmergy: A Wide Area Service Discovery Protocol for Active Networks

The touted goal that drives the field of Active Networks lies in the concept of dynamic service provisioning. In this, when an Active Node is presented with a request for a service, it will be able to either provide the service: (i) immediately – if the requested service is available locally; or (ii) after an initial delay – caused due to discovery, deployment and instantiation of the service dynamically. The delay to dynamically discover and deploy Active Services can affect the overall quality of service perceived by end applications. Hence, efficient service discovery mechanisms are essential for proper operation. In this paper we present a service discovery protocol, referred to as Stigmergy, which supports the discovery of Active Services in the network. The key feature of the Stigmergy protocol is that each Autonomous System in the network is treated as an independent two level caching structure in which the upper level, L1, contains pointers to active services that are present in the lower level, L0. This protocol, by self-organising network nodes that are under a common administrative control into virtual cache clusters, maximises the chances of discovering the required services within minimal latencies. Furthermore, the Stigmergy protocol is completely distributed and follows a best-effort cache co-operation model. Finally, this protocol avoids the need to configure and maintain independent caching frameworks for service discovery purposes. I

RSVP Reservation Gaps: Problems and Solutions

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. I