Dealing with Heterogeneity in a Fully Reliable Multicast Protocol

Many of the proposed multicast congestion avoidance algorithms are single-rate where heterogeneity is accommodated by adjusting the transmission rate as a response to the worst receiver in the group. Due to the Internet heterogeneity, a single-rate congestion co ntrol affects the overall satisfaction of the receivers in a multicast session. In this paper, we propose a multi-rate replicated scheme where some receivers (instead of the source) are designated to perform data replication for other receivers with lower capacity. To be more scalable and to minimize the bandwidth consumption due to data replication, the partitioning algorithm is per- formed on-the-fly by the routers depending on the feedback they receive. Neither a prior estimation of the receivers capacity is necessary nor a complex computation is required to execute our partitioning algorithm

A Loss Detection Service for Active Reliable Multicast Protocols

Reliable multicast protocols have gained popularity with active service contributions where routers implement additional functionalities. Reducing the delay of recovery is one of the desirable features of a reliable multicast protocol. In this paper we propose an active-based architecture with specialized routers. Using simulations we show how this architecture with the proposed services (mainly the loss recovery from the receivers and the loss detection at the routers), could improve the performances of a reliable multicast application in term of the recovery delay

Signaling strategies for consumer oriented Grid over Optical Burst Switching networks

Dissertação mest., Engenharia Eléctrica e Telecomunicações, Universidade do Algarve, 2009The concept of Grid networks has recently emerged as an infrastructure able to support, both scientific and commercial applications. The Grid is a dynamic, distributed collection of heterogeneous computational, storage and network resources geographically distributed and shared between organizations. Optical Burst Switching (OBS) networks have been identified as a technology with potential to support the requirements of the Grids. This approach, known as Grid over Optical Burst Switching (GOBS) is currently the object of intensive research. This dissertation focus is on GOBS architectures employing Active OBS Routers with centralized control. This approach enables the balance of the overall network traffic potentially minimizing congestion and consequently reducing job blocking. Two different strategies are explored. The first strategy is a novel signaling scheme applied to a GOBS network employing Active Routers. The Active Router reduces the job blocking probability, because the path used by the Data Burst to reach the Grid Job Resource is selected based on the network actual status. Since the Active Router maintains the network status always updated, the bursts are only dropped when is not possible to connect the source to the end node. Another study associated with this signaling scheme is the reservation time. It is demonstrated that this approach decreases the network blocking probability at the same time that decreases the time delay that a job suffers until it reaches the Grid service provider. In the second strategy, the Active Router only select the Grid Resource used to resolve the job, the path used to reach it is selected by the Grid client based on the probabilistic model for the link demands. The probabilistic model is used to predict a possible network usage based on the demands from all nodes to all nodes. The results obtained show overall performance improvement

Dynamic Replier Active Reliable Multicast (DyRAM)

Desirable features of reliable multicast include low end-to-end delays, high throughput and scalability, and meeting these objectives is not an easy task. We propose a receiverbased (replier) local recovery multicast protocol with dynamic repliers elected on a per-packet basis. Designed to provide an efficient reliable multicast service without any cache facilities in the multicast tree, our approach, noted DyRAM, uses low-overhead active services in routers. After presenting the protocol and some designed and implementation issues the paper compares DyRAM to ARM, the nearest active reliable multicast protocol in term of functionalities proposed in the active multicast community. Simulation results show that DyRAM performs much better than an ARM-like protocol which needs a significant amount of cache to exhibit performances. Additionally, in case some cache is available for DyRAM and ARM, the study shows that DyRAM always performs better than ARM