This paper presents the design, implementation and performance of a reliable multicast transport protocol called RMTP. RMTP is based on a hierarchical structure in which receivers are grouped into local regions or domains and in each domain there is a special receiver called a Designated Receiver (DR) which is responsible for sending acknowledgments periodically to the sender, for processing acknowledgements from receivers in its domain and for retransmitting lost packets to the corresponding receivers. Since lost packets are recovered by local retransmissions as opposed to retransmissions from the original sender, end-to-end latency is significantly reduced, and the overall throughput is improved as well. Also, since only the DRs send their acknowledgments to the sender, instead of all receivers sending their acknowledgments to the sender, a single acknowledgement is generated per local region, and this prevents acknowledgement implosion. Receivers in RMTP send their acknowledgments to the DRs periodically, thereby simplifying error recovery. In addition, lost packets are recovered by selective repeat retransmissions, leading to improved throughput at the cost of minimal additional buffering at the receivers. This paper also describes the implementation of RMTP and its performance on the Internet.

This paper presents the Reliable Multicast Protocol (RMP). RMP provides a totally ordered, reliable, atomic multicast service on top of an unreliable multicast datagram service such as IP Multicasting. RMP is fully and symmetrically distributed so that no site bears an undue portion of the communication load. RMP provides a wide range of guarantees, from unreliable delivery to totally ordered delivery, to K-resilient, majority resilient, and totally resilient atomic delivery. These QoS guarantees are selectable on a per packet basis. RMP provides many communication options, including virtual synchrony, a publisher/subscriber model of message delivery, a client/server model of delivery, an implicit naming service, mutually exclusive handlers for messages, and mutually exclusive locks.

Network support for multicast has triggered the development of group communication applications such as multipoint data dissemination and multi-party conferencing tools. To support these applications, several multicast transport protocols have been proposed and implemented. Multicast transport protocols have been an area of active research for the past couple of years. This document tries to summarize the activities in this work-in-progress area by surveying several multicast transport protocols. The paper also presents a taxonomy to classify the surveyed protocols according to several distinct features, discusses the rationale behind the protocol's design decisions, and presents some current research issues in multicast protocol design. 1 Introduction Multicast transport mechanisms have been a topic of intense research and development efforts over the past couple of years. Both the Internet Engineering and Internet Research Task Forces (IETF and IRTF) have been heavily involved in co...

Abstract—This paper presents a protocol and design for concurrent and reliable group multicast (many-to-many) frombursty data sources in general networks. In a group multicast, any node can be a multicast source and multiple nodes may start to multicast simultaneously, i.e., an asynchronous access to the network. The reliable multicast protocol presented in this work is window based with a combined sender and receiver initiation of the recovery protocol. In reliable multicasting the necessary requirement is to ensure that data is received correctly by all the active members of the multicast group. The approach taken in this work is to combine the multicast operation with the internal flow control. As a result, it is possible to provide: 1) congestion-free multicast routing with a single and immediate acknowledgment message to the sender. Furthermore, in every multicast, 2) a node can access all the capacity allocated to its group with no delay, however, if several nodes are active in the same group, then the capacity will be shared fairly. In addition, 3) each sender in the multicast group uses a single timer, and 4) a node can become active or inactive in a transparent fashion, i.e., there is no need to explicitly notify the members of the group. A multiple criteria optimization study of the bandwidth allocation to each multicast group is presented. The optimization problem has two Min–Max objective functions: 1) for delay, which is caused by the number of links needed to connect the group, and 2) for congestion, which is caused by sharing a link among multiple multicast groups. The bandwidth allocation among multicast groups sharing the same link are further optimized using the Max–Min fairness criterion. Index Terms — Fairness, multicast, reliable protocol, ring embedding, reliable multicast, ring network, virtual ring. I.

This paper describes the design and implementation of a multicast transport protocol called RMTP. RMTP provides sequenced, lossless delivery of bulk data from one sender to a group of receivers. RMTP achieves reliability by using a packet based selective repeat retransmission scheme, in which each acknowledgment (ACK) packet carries a sequence number and a bitmap. ACK handling is based on a multi-level hierarchical approach, in which the receivers are grouped into a hierarchy of local regions, with a Designated Receiver (DR) in each local region. Receivers in each local region periodically send ACKs to their corresponding DR, DRs send ACKs to the higher-level DRs, until the DRs in the highest level send ACKs to the sender, thereby avoiding the ACK-implosion problem. DRs cache received data and respond to retransmission requests of the receivers in their corresponding local regions, thereby decreasing end-to-end latency and improving resource usage. This paper also provides the measurem...

We present a novel architecture for providing a reliable multicast transport service over existing protocol stacks. These protocol stacks ordinarily support reliable unicast transport layer connections over a network layer which is capable of providing an unreliable multicasting service. We propose the addition of a new Single Connection Emulation (SCE) sublayer between the unicast transport layer and the multicast network layer. This added layer mimics the single destination network layer interface to the transport layer and interfaces with the multicast network layer to provide the necessary multicast functionality. The new architecture also enables interactions between applications and the SCE, thus allowing the applications to control the semantics of the reliable multicast connection. We discuss the design issues that need to be considered when such a sublayer is to be introduced. We also discuss an implementation of this new approach using the TCP/IP protocol stack.and present so...

This paper presents the design and analysis of three reliable multicast transport protocols for high speed networks. The novelty of these protocols lies in the technique used in combining the acknowledgments of individual destinations along the underlying multicast tree to prevent acknowledgement implosion and in the technique used in preventing unnecessary retransmission by performing local multicasts. These protocols use the periodic exchange of complete state information [NRS90] between the source and the destinations and a block-based Selective Repeat retransmission scheme to improve the overall performance in a high speed networking environment. Performance of each protocol is analyzed in terms of throughput, end-to-end delay, buffer requirement, acknowledgment traffic and retransmission traffic. Based on this analysis and the complexity of implementation, one of the three protocols is recommended for reliable multicasting in high speed networks. 1 Introduction Multicasting is an...

Abstract — This paper presents the design, implementation, and performance of a reliable multicast transport protocol (RMTP). RMTP is based on a hierarchical structure in which receivers are grouped into local regions or domains and in each domain there is a special receiver called a designated receiver (DR) which is responsible for sending acknowledgments periodically to the sender, for processing acknowledgment from receivers in its domain, and for retransmitting lost packets to the corresponding receivers. Since lost packets are recovered by local retransmissions as opposed to retransmissions from the original sender, end-to-end latency is significantly reduced, and the overall throughput is improved as well. Also, since only the DR’s send their acknowledgments to the sender, instead of all receivers sending their acknowledgments to the sender, a single acknowledgment is generated per local region, and this prevents acknowledgment implosion. Receivers in RMTP send their acknowledgments to the DR’s periodically, thereby simplifying error recovery. In addition, lost packets are recovered by selective repeat retransmissions, leading to improved throughput at the cost of minimal additional buffering at the receivers. This paper also describes the implementation of RMTP and its performance on the Internet. Keywords- multicast routing, MANET, acknowledgement implosion, designated receiver I.