RAMP: a reliable adaptive multicast protocol

In the last two decades, Multi-Cast schemes in mobile ad-hoc networks have been widely studied and lots of research results have been put into use and changed our everyday life. However, packet loss for Multi-Cast schemes in mobile ad-hoc networks has not been well studied yet. The influence of node density and relay schemes on packet loss is not clear. Thus, we study the packet loss problem for Multi-Cast schemes in MANETs in this paper. First, we present a general Multi-Cast probabilistic model to get a better understanding of the packet loss problem. Second, based on the general model and Chernoff Bounds, we prove that the up'er bound of the general packet loss for Multi-Cast is Ω(me <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">- 2</sup> ), where n is the node number and m denotes number of hops. Thus we can conclude that large node density decreases the packet loss rate by exponential factor, and bigger hops increase packet loss rate linearly. In addition, we present a reliable Multi-Cast protocol(RMP). Through an ACK Aware Tree to complete packet acknowledgement and repair host selection, RMP is able to minimize the impact of packet loss on the Multi-Cast throughput in the simulation.

Feedback implosion is one of the crucial issues related to the scalability of reliable multicast protocols. Generally speaking, in timer-based solutions, when a receiver needs to send feedback, it multicasts the feedback to all receivers early enough, hence suppressing others from returning feedback in response to the same event. In this paper we present an effective end-to-end negative acknowledgment (NACK) control algorithm which could solve the problem caused by correlative packet loss and independent packet loss among receivers.

Packet loss in wired communication networks is almost entirely caused by buffer overflow in intermediate network nodes. Although the packet loss ratio at a (bottleneck) buffer is an important performance measure, it is often an insufficient measure to accurately assess the impact of loss on overall network performance. This contribution therefore focuses on various flow level packet loss characteristics of a network node. The network node is modelled as a quasi-birth-death finite-capacity queueing system such that various levels of arrival correlation can be captured while maintaining analytical tractability. Some numerical examples illustrate the approach considered.

A reliable multicast protocol enables a process to multicast a message to a group of processes in a way that ensures that all honest destination-group members receive the same message, even if some group members and the multicast initiator are maliciously faulty. Reliable multicast has been shown to be useful for building multiparty cryptographic protocols and secure distributed services. We present a high-throughput reliable multicast protocol that tolerates the malicious behavior of up to fewer than one-third of the group members. Our protocol achieves high-throughput using a novel technique for chaining multicasts, whereby the cost of ensuring agreement on each multicast message is amortized over many multicasts. This is coupled with a novel flow-control mechanism that yields low multicast latency.

Multicasting plays an important role in internet networks. Supporting wavelength division multiplexed (WDM) multicasting in an IP over WDM network poses interesting problems because some WDM switches may be incapable of switching an incoming signal to more than one output interface. Although some multicast applications, such as audio/video conferencing can tolerate packet error or loss, other applications such as one-to-many file transfer and military applications do not. Hence, an inevitable need for reliable multicasting arises. The reliable multicast protocol ensures the eventual delivery of multicast data to all multicast group members. The reliable multicast is receiver initiated NACK-based and it makes use of feedback suppression in order to avoid NACK and retransmission implosion. The loss recovery burden is distributed over the multicast group members in order to reduce recovery latency and end-to-end delay. The proposed protocol is evaluated in terms of performance metrics for an IP/WDM optical network which will be the candidate for the next generation internet networks.

This paper describes the process of implementing a complex communications protocol that provides reliable delivery of data in multicast-capable, packet-switching telecommunication networks. The protocol, called the Reliable Multicasting Protocol (RMP), was developed incrementally using a combination of formal and informal techniques in an attempt to ensure the correctness of its implementation. Our development process involved three concurrent activities: (1) the initial construction and incremental enhancement of a formal state model of the protocol machine; (2) the initial coding and incremental enhancement of the implementation; and (3) model-based testing of iterative implementations of the protocol. These activities were carried out by two separate teams: a design team and a V&amp;amp;V team. The design team built the first version of RMP with limited functionality to handle only nominal requirements of data delivery. In a series of iterative steps, the design team added new functionality to the implementation while the V&amp;amp;V team kept the state model in fidelity with the implementation. This was done by generating test cases based on suspected errant or off-nominal behaviors predicted by the current model. If the execution of a test was different between the model and implementation, then the differences helped identify inconsistencies between the model and implementation. The dialogue between both teams drove the co-evolution of the model and implementation. Testing served as the vehicle for keeping the model and implementation in fidelity with each other. This paper describes (1) our experiences in developing our process model; and (2) three example problems found during the development of RMP.

The number of mobile devices accessing the Internet is continuously increasing, creating new problems. For example, when many wireless clients try to access the same video stream in the same hot spot, multicast transmission must be used. However, multicast packets are unacknowledged and may present a high loss rate under adverse conditions which may jeopardize the quality of the streaming. In a severe scenario, packet losses may affect all video frames, preventing the clients from receiving the video stream at all. Therefore, we propose a novel reliable multicast protocol, tailored to streaming applications, that also scales to many clients under the same access point. It uses a feedback repeat request mechanism per client and such requests are adequately scheduled by the streaming server. This mechanism, which is the focus of this paper, also allows differentiating the quality of service provided to the clients, polling their feedback independently. We show experimental and simulation results that confirm the desired scalability and reliable streaming, with efficient bandwidth usage. The results also show a clear superiority in mitigating lost packets with respect to other approaches to the same problem, with benefits reaching and even going beyond one order of magnitude in packets recovery.

To reduce or eliminate the implosion of acknowledgments at the source of a very large multicast group, current reliable multicast protocols either organize the receivers of a group into a tree or ring, or implement negative acknowledgment (NAK) avoidance algorithms based on random timers. All of these approaches have their limitations and advantages. We present a ring-based reliable multicast protocol, called the evenly-loaded ring protocol (ELRP) which removes processing bursts from nodes in the ring. ELRP achieves throughputs as good as those obtained with tree-based protocols and better than those of receiver-initiated protocols with NAK avoidance. We propose a deterministic NAK avoidance (DNKA) algorithm based on ELRP that performs better than the random NAK avoidance scheme (RNKA). Because tree structures are better suited than rings for wide areas involving paths with long delays, we propose the hybrid reliable multicast protocol (HRMP) which organizes receivers into a backbone acknowledgement tree that connects local areas. Any tree-based protocol with positive acknowledgement can be run in the backbone acknowledgement tree, and ELRP is run in the local areas. The maximum achievable throughput in HRMP is analyzed, which shows that it is completely scalable. The delay of DNKA and RNKA schemes are also analyzed which shows that compared with RNKA, DNKA reduces the retransmission delay significantly.

Multicast in wireless sensor networks (WSNs) is an efficient way to spread the same data to multiple sensor nodes. It becomes more effective due to the broadcast nature of wireless link, where a message transmitted from one source is inherently received by all one-hop receivers, and therefore, there is no need to transmit the message one by one. Reliable multicast in WSNs is desirable for critical tasks like code updation and query based data collection. The erroneous nature of wireless medium coupled with limited resource of sensor nodes, makes the design of reliable multicast protocol a challenging task. In this work, we propose a time division multiple access (TDMA) based energy aware media access and control (TEA-MAC) protocol for reliable multicast in WSNs. The TDMA eliminates collisions, overhearing and idle listening, which are the main sources of reliability degradation and energy consumption. Furthermore, the proposed protocol is parametric in the sense that it can be used to trade-off reliability with energy and delay as per the requirement of the underlying applications. The performance of TEA-MAC has been evaluated by simulating it using Castalia network simulator. Simulation results show that TEA-MAC is able to considerably improve the performance of multicast communication in WSNs.

A three-stage packet switch architecture that uses a two stage, self-routing, memoryless, interconnection network to interconnect a third stage of smaller packet switches was proposed by K.Y. Eng. et al. (Proc. IEEE Globecom, p.1159-65, vol.2, 1989). Two new routing algorithms that facilitate the multicastings of packets with this architecture are proposed. The two routing algorithms, one of which duplicates packets at only the first stage and the other which duplicates packets at the first and third stages, require only minimal alterations to the switch. An analysis is made of the switch's multicast performance, finding an overbound on the packet loss probability. The analysis, which identifies three sources of packet loss, shows that good multicast performance is maintained with only a small increase in the architecture's expansion provided that, on average, the load is not severely concentrated onto any particular input section as a result of multicasting. >

This paper introduces a reliable multicast transport protocol RCCMP (reliable congestion controlled multicast protocol) that has been designed to be simple, scalable, reliable and TCP-friendly. The congestion control is a central part of the protocol, where the feedback of the worst receiver is used to control a transmission window in a TCP-like fashion. The scalability issue is addressed with an exponential timers scheme, that is also used to estimate the number of receivers involved in the communication. The protocol neither needs support from network elements nor maintains state information dependent of the number of receivers. The paper presents a number of simulation results on its performance. Besides, some design choices are evaluated.

Two reliable multicast protocols for wireless local area networks (LANs) are proposed: a leader-based protocol with a sliding window, LBPW; a leader-based protocol with a sliding window and n-fold acknowledgement reduction, LBPR(n). They are based on a previously proposed leader-based protocol (LBP). Firstly, a pipelining technique is added into the LBP to form the LBPW so as to make frame transmission efficient. Then, an acknowledgement reduction scheme is incorporated into LBPW to form LBPR(n) to alleviate the ACK/NAK implosion problem. Through numerical examples done by a simulation approach, we demonstrate that these two reliable multicast protocols outperform LBP.

In current IEEE 802.11 WLAN, the unicast provides a reliable way of communication thanks to the use of acknowledgement feedbacks. As to the multicast, it suffers from unreliability and inefficiency. Recently many protocols have been designed for 802.11 such as Leader Based Protocol (LBP), to provide a reliable multicast transport. Yet no optimal solution has been proposed. In this paper we present Reliable PLCP-based Multicast Protocol (RPMP), a new reliable multicast protocol as an extension to the 802.11g and 802.11a. RPMP achieves reliability through the use of Negative Acknowledgements (NAK). We reduce the transmission overhead of our protocol, compared to other NAK-based proposals, by adding one additional OFDM symbol in the Physical Layer Convergence Procedure (PLCP) header of the multicast frame instead of using additional control frames. Further we show, based on our simulation results that the delivery ratio of RPMP remains at 100% in a lossy channel when it falls down to 50% with the standard. We also show that the efficiency of RPMP is much more enhanced than that of LBP.

Applications requiring the reliable distribution of data to groups of clients would be supported perfectly by reliable multicast protocols. In many cases, the problem of congestion control (a major research issue otherwise) does not exist because downlink bandwidth is owned or can be preallocated to a particular server by independent means, but the problems of insuring reliable data delivery to larcre groups, and adaptability to heterogeneous clients, still remain. These problems can be solved at once with the use of FEC techniques. In this paper we show the design of a Reliable Multicast data Distribution Protocol (RMDP) that we have built using these techniques, and discuss the implementation tradeoffs. Experimental results show that, albeit somewhat expensive, doing encoding/decoding in software is affordable for speeds in the Mbit/s range even on low-end PCs. Slower machines can still receive at high speed, thus optimizing network usage, by taking advantage of the fact that decoding needs not to be done in real time. Finally, our RMDP can work even without any feedback from the receivers, thus making it well suited to mobile/wireless systems.

Sender-initiated reliable multicast protocols, based on the use of positive acknowledgments (ACKs), lead to an ACK implosion problem at the sender as the number of receivers increases. Briefly, the ACK implosion problem refers to the significant overhead incurred by the sending host due to the processing of ACKs from each receiver. A potential solution to this problem is to shift the burden of providing reliable data transfer to the receivers—thus resulting in a receiver-initiated multicast error control protocol based on the use of negative acknowledgments (NAKs). In this paper we determine the maximum throughputs of the sending and receiving hosts for generic sender-initiated and receiver-initiated protocols. We show that the receiver-initiated error control protocols provide substantially higher throughputs than their sender-initiated counterparts. We further demonstrate that the introduction of random delays prior to generating NAKs coupled with the multicasting of NAKs to all receivers has the potential for an additional substantial increase in the throughput of receiver-initiated error control protocols over sender-initiated protocols.