We survey a number of packet-loss recovery techniques for streaming audio applications operating using IP multicast. We begin with a discussion of the loss and delay characteristics of an IP multicast channel and from this show the need for packet loss recovery. Recovery techniques may be divided into two classes: senderand receiver-based. We compare and contrast several sender-based recovery schemes: forward error correction (both media specific and media independent) interleaving and retransmission. In addition a number of error concealment schemes are discussed. We conclude with a series of recommendations for repair schemes to be used, based on application requirements and network conditions. 1 Introduction The development of IP multicast and the Internet multicast backbone has led to be emergence of a new class of scalable audio/video conferencing applications. These are based on the lightweight sessions model [11, 17] and provide efficient multi-way communication which scales fr...

(PRM): a multicast data recovery scheme that improves data delivery ratios while maintaining low end-to-end latencies. PRM has both a proactive and a reactive components; in this paper we describe how PRM can be used to improve the performance of application-layer multicast protocols especially when there are high packet losses and host failures. Through detailed analysis in this paper, we show that this loss recovery technique has efficient scaling properties—the overheads at each overlay node asymptotically decrease to zero with increasing group sizes. As a detailed case study, we show how PRM can be applied to the NICE application-layer multicast protocol. We present detailed simulations of the PRM-enhanced NICE protocol for 10 000 node Internet-like topologies. Simulations show that PRM achieves a high delivery ratio ( 97%) with a low latency bound (600 ms) for environments with high end-to-end network losses (1%–5%) and high topology change rates (5 changes per second) while incurring very low overheads ( 5%). Index Terms—Multicast, networks, overlays, probabilistic forwarding, protocols, resilience. I.

The IP-multicast architecture is extended with addressing information along multicast routing trees that permits more efficient and sophisticated multicast routing options and encourages communication and cooperation between IP and higher-layer protocols. The Addressable Internet Multicast (AIM) architecture is introduced that enables sources to restrict the delivery of packets to a subset of the receivers in a multicast group on a per-packet basis, permits receivers to listen to subsets of sources on a subscription basis, provides nearest-host routing, and allows higher-layer protocols to place packets into application-defined logical streams, so that hosts may direct the multicast routing of packets based on application-defined contexts. In addition, the Reliable Multicast Architecture (RMA) is introduced to support end-toend reliable multicasting using heterogeneous reliable multicast protocols and providing acknowledgment trees implicitly, thereby eliminating the ACK implosion prob...

The ability to trace multicast paths is currently available in the Internet by means of IGMP MTRACE packets. We introduce Tracer, the first protocol that organizes the receivers of a multicast group deterministically into a logical tree structure while maintaining exact packet-loss correlation for local error recovery, and without requiring any changes to existing multicast routing protocols. Tracer uses MTRACE packets in IGMP to allow a receiver host to obtain its path to the source of a multicast group. Receivers use the multicast path information to determine how to achieve local error recovery and effective congestion control. We compare the tracing approach with prior mechanisms that attempt local recovery. Results of measurements carried out over the CAIRN illustrate the fact that tracing multicast paths is an effective tool to organize receivers based on their packet-loss correlation. 1 Introduction As support in the Internet for multicast, or one-to-many, communication betwee...

This paper introduces the newscast model of computation for large-scale computing on the Internet. The engine realizing this model is a lazy fully distributed information propagation protocol among the participants which is responsible for membership management and communication. It maintains a constantly changing communication graph over the participants. This graph has useful emergent properties like small diameter and sufficiently random structure without deploying special purpose protocols to achieve these properties. For adding a new participant only the address of an arbitrary member is needed and for removal no action is necessary. We provide theoretical and empirical evidence that besides being simple and lightweight our newscast computing engine is extremely scalable and robust. We also suggest some interesting application areas including information dissemination, monitoring of large systems, resource sharing and efficient multicasting.

We outline a scheme by which encrypted multicast audiovisual data may be watermarked by lightweight active network components in the multicast tree. Every recipient receives a slightly different version of the marked data, allowing those who illegally re-sell that data to be traced. Groups of cheating users or multicast routers can also be traced. There is a relationship between the requirements for the scheme proposed here, the requirements for reliable multicast protocols, and proposed mechanisms to support layered delivery of streamed media in the Internet.

The publish-subscribe model provides strong decoupling among the components of a distributed application. This characteristic makes it amenable to highly dynamic environments. Nevertheless, publish-subscribe systems exploiting a distributed event dispatcher are typically not able to rearrange dynamically their operations to adapt to changes impacting the topology of the dispatching infrastructure. This paper presents a description and analysis of a novel algorithm to deal with this kind of reconfiguration. The strength of this algorithm is its ability to minimize the portion of the system affected by the reconfiguration by exploiting a novel concept we refer to as the reconfiguration path. Simulations compare our approach with two others from the literature and show a significant reduction (up to 76%) in the overhead caused by reconfiguration.

The phenomenal growths of group communications and QoS-aware applications over the Internet have respectively accelerated the development of two key technologies, namely, multicasting and Differentiated Services (DiffServ). Although both are complementary technologies, the integration of the two technologies is a nontrivial task due to architectural conflicts between multicasting and DiffServ. In this paper, we propose an approach for providing multicast support across a DiffServ domain that is scalable in terms of group size, network size, and number of groups. We analyze our approach in a detailed manner for feasibility, adaptiveness, and deployment considerations.

In multicasting routing, the main objective is to send data from one or more source to multiple destinations, while at the same time minimizing the usage of resources. Examples of resources which can be minimized include bandwidth, time and connection costs. In this paper we survey applications of combinatorial optimization to multicast routing. We discuss the most important problems considered in this area, as well as their models. Algorithms for each of the main problems are also presented.

Unpredictable network latency is the most challenging problem in multiplayer game networking design.  Latencies can be reduced by using a peer-to-peer rather than a client-server architecture.  However, peer-to-peer architectures raise a whole new set of issues, the most immediate being game state synchronization. The drawbacks of the peer-to-peer architecture are addressed in our game system.  The game system includes 1) a new mirrored-server architecture, 2) a trailing state synchronization protocol and 3) a many-to-many reliable multicast protocol.  As a proof-of-concept, we converted Quake, a client-server game, to our mirrored-server architecture.