This paper looks at reliability with a new goal: development of a multicast protocol which is reliable in a sense that can be rigorously quantified and includes throughput stability guarantees. We characterize this new protocol as a "bimodal multicast" in reference to its reliability model, which corresponds to a family of bimodal probability distributions. Here, we introduce the protocol, provide a theoretical analysis of its behavior, review experimental results, and discuss some candidate applications. These confirm that bimodal multicast is reliable, scalable, and that the protocol provides remarkably stable delivery throughput

Epidemic-style (gossip-based) techniques have recently emerged as a scalable class of protocols for peer-to-peer reliable multicast dissemination in large process groups. These protocols provide probabilistic guarantees on reliability and scalability. However, existing implementations of epidemic-style dissemination are reputed to suffer from two major drawbacks: a) (Network Overhead) when deployed on a WAN-wide or VPN-wide scale they cause a large number of packets to transit across the boundaries of network domains (eg., LANs, subnets, ASs), causing an overload on core network elements such as bridges, routers, and links, and b) (Lack of Adaptivity) they impose the same load on process group members and the network regardless of the failure characteristics of the underlying network. In this paper, we report on the first comprehensive set of solutions to these problems. The solution includes two protocols: a) a Hierarchical Gossiping protocol, and b) an Adaptive multicast Dissemination Framework that can be used with any gossiping primitive. Our solution organizes nodes in a hierarchy which re ects the network topology and guarantees low trac across domain boundaries in the network. In the interests of space, this paper focuses on the Hierarchical Gossiping protocol in detail through mathematical and simulation analysis that evaluate the improvement over a traditional gossiping protocol. We present an overview of the working and properties of the Adaptive Dissemination protocol.

This paper focuses on the scalability of distributed protocols, in group communication systems, providing some form of guaranteed reliability. Examples include the virtual synchrony protocols for reliable group communication [1], scalable reliable multicast (SRM) [2], and reliable multicast transport protocol (RMTP) [3]. We argue that the usual architecture for supporting reliability exposes mechanisms of this sort to serious scalability problems

Epidemic-style (gossip-based) techniques have recently emerged as a class of scalable and reliable protocols for peer-to-peer multicast dissemination in large process groups. However, popular implementations of epidemic-style dissemination suffer from two major drawbacks: (a) Network Overhead: When deployed on a WANwide or VPN-wide scale they generate a large number of packets that transit across the boundaries of multiple network domains (e.g., LANs, subnets, ASs), causing an overload on core network elements such as bridges, routers, and associated links; (b) Lack of Adaptivity: They impose the same load on process group members and the network even under reduced failure rates (viz., packet losses, process failures). In this paper, we describe two protocols to address these problems: (1) a Hierarchical Gossiping protocol, and (2) an Adaptive Dissemination framework (for multicasts) that allows use of any gossiping primitive within it. These protocols work within a virtual peer-to-peer hierarchy called the Leaf Box Hierarchy. Processes can be allocated in a topologically aware manner to the leaf boxes of this structure, so that (1) and (2) produce low traffic across domain boundaries in the network, and induce minimal overhead when there are no failures.

Most existing communications technologies are either not scalable at all, or scale only under carefully controlled conditions. This threatens an emerging generation of mission-critical but very large computing systems, which will need communication support for such purposes as system management and control, policy administration, data dissemination, and to initiate adaptation in demanding environments. Cornell University’s Spinglass project has discovered that “gossip-based ” protocols can overcome scalability problems, offering security and reliability even in the most demanding settings. Gossip protocols emulate the spread of an infection in a crowded population, and are both reliable and stable under forms of stress that can disable more traditional protocols. Our effort is developing a new generation of gossip-based technology for secure, reliable large-scale collaboration and soft real-time communications – even over global networks. 1.

Abstract—Growing demand for multicast communication in large network settings has focused attention on the scalability of reliable multicast protocols. Our paper uses both simulation tools and experiments to compare two scalable protocols, focusing on an aspect not often studied: we emphasize stability of latency distributions as these protocols scale, although also considering overhead and link utilization. These properties are considered in a variety of network topologies and with several levels of packet loss. Our findings confirm that SRM scales poorly under some conditions: to obtain reliability, the protocol incurs overhead linear in group size and throughput fluctuates erratically. We also show that SRM latencies can be very large and that latency distributions are unstable as a function of group size and network topology. Our own protocol, Bimodal Multicast, also exhibits overhead growth, but the rate of growth is slow, and latency distributions and delivery throughput rates are stable. Index terms—scalable reliable multicast, bimodal multicast, throughput stability, SRM, pbcast. A.

Reliable multicast protocols on top of the MBone are presently subject to intensive research. In the past, numerous protocols have been developed and their respective performance been analysed. Little progress has been made, though, to compare different approaches. In this paper, we use the network simulator ns-2 to evaluate the performance of three protocols, namely Scalable Reliable Multicast (SRM), Multicast File Transfer Protocol (MFTP) and an enhanced version of the latter, called Multicast File Transfer Protocol with Erasure Correction (MFTP/EC). We also compare the results to each other and test the suitability for multicast file distribution. Keywords: Reliable Multicast, Network Simulator, Scalability 1 Introduction Protocols for the reliable one-to-many data transfer can be constructed in various ways, and existing protocol architectures in fact use completely different techniques. As a consequence, they differ in bandwidth consumption and quality of service they offer to t...

Building very large computing systems is extremely challenging, given the lack of scalable communication technologies. This threatens a new generation of mission-critical but very large computing systems. Fortunately, a new generation of “gossip-based ” or epidemic protocols can overcome scalability problems, offering security and reliability even in the most demanding settings. Epidemic protocols emulate the spread of an infection in a crowded population, and are both reliable and stable under forms of stress that will disable most traditional protocols. Cornell University’s Spinglass project is developing a new generation of epidemic-based technology for secure, reliable large-scale collaboration and soft real-time communications – even over global networks. 1

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The popularity of large-scale distributed applications, such as videoconferencing, multimedia dissemination, electronic stock exchange and distributed cooperative work, has grown with the availability of high-speed networks and the expansion of the Internet. The key property of this type of applications is the need to distribute data among multiple participants together with an application-specific quality of service needs. This fact makes scalable multicast protocols an essential underlying communication structure. Although there exist several studies investigating the traffic characteristics of unicast communication, multicast traffic has not been examined extensively in previous studies. It is well known that the aggregate traffic properties of self-similarity and long-range dependence are ubiquitous in wide area networks and lead to adverse consequences in network performance. In this study, we analyze traffic characteristics of a novel scalable, reliable multicast protocol, Bimodal Multicast (Pbcast). In particular, our simulation studies demonstrate that epidemic approach of Bimodal Multicast generates short-range dependent traffic with low overhead traffic and transport delays. We elaborate on the protocol mechanisms as an underlying factor in our empirical results.