# Multicast Papers Appeared in 1993

Ra'ed Y. Awdeh and H. T. Mouftah, "A non-typical approach for the design of multicast ATM switch architectures," in Proc. of ISCA/ACM SIGCOMM Second International Conference on Computer Communications and Networks (IC3N), (San Diego, California), pp. 399-404, June 1993.

Keywords: ATM switching, delta networks, multicasting, point-to-multipoint, performance evaluataion

Mostafa H. Ammar, "Probabilistic multicast: generalizing the multicast paradigm to improve scalability," in 8th IEEE Workshop on Computer Communications, (Del Mar, California), IEEE, Oct. 1993.

Keywords: multicast; scaling

Rosario Aiello, Elena Pagani, and Gian Paolo Rossi, "Causal ordering in reliable group communications," in SIGCOMM Symposium on Communications Architectures and Protocols (Deepinder P. Sidhu, ed.), (San Francisco, California), pp. 106-115, ACM, Sept. 1993. also in \em Computer Communication Review 23 (4), Oct. 1992.

Abstract: In this paper we present a solution to the causal reliable multicast problem. User processes generate separate sequences of messages and specify the causal relation among them according to some application need; the algorithm ensures that the messages within the same sequence are delivered to all active, i.e., both correct and faulty, processes in the group, or to none of them, and are processed according to their causal order. Messages belonging to different sequences can be concurrently processed. This problem has few solutions presented in the literature; in common with a part of them, the algorithm we describe has the centralized approach and the use of history buffers to recover from omission failures. The differences mainly concern the mechanism we devised to recover from crash failures, that avoids resorting to specialized protocols. As a consequence, under failure conditions, the algorithm performs better than other proposals in terms of both network load and throughput without affecting the performances under reliable conditions. Further, it allows to implement the most general interpretation of causality and it does not require any particular service to the underlying transport protocol.
Keywords: multicast; causality; reliable multicast; group communications; distributed algorithms

C. Mic Bowman, Peter B. Danzig, and Michael F. Schwartz, "Research problems for scalable Internet resource discovery," in Proceedings of the International Networking Conference (INET), (San Francisco, California), pp. DFB-1 - DFB-10, Internet Society, Aug. 1993.

Abstract: Over the past several years, a number of information discovery and access tools have been introduced in the Internet, including Archie, Gopher, Netfind, and WAIS. These tools have become quite popular, and are helping to redefine how people think about wide area network applications. Yet, they are not well suited to supporting the future information infrastructure, which will be characterized by enormous data volume, rapid growth in the user base, and burgeoning data diversity. In this paper we indicate trends in these three dimensions, and survey problems these trends will create for current approaches. We then suggest several promising directions of future resource discovery research, along with some initial results from projects carried out by members of the Internet Research Task Force Research Group on Resource Discovery and Directory Service.
Keywords: Internet; resource discovery; gopher; archie; WAIS; data indexing; database; caching; replication; multicast; data distribution

Tony Ballardie, Paul Francis, and Jon Crowcroft, "Core based trees (CBT)," in SIGCOMM Symposium on Communications Architectures and Protocols (Deepinder P. Sidhu, ed.), (San Francisco, California), pp. 85-95, ACM, Sept. 1993. also in \em Computer Communication Review 23 (4), Oct. 1992.

Abstract: One of the central problems in one-to-many wide-area communications is forming the delivery tree - the collection of nodes and links that a multicast packet traverses. Significant problems remain to be solved in the area of multicast tree formation, the problem of scaling being paramount among these. In this paper we show how the current IP multicast architecture scales poorly (by scale poorly, we mean consume too much memory, bandwidth, or too many processing resources), and subsequently present a multicast protocol based on a new scalable architecture that is low-cost, relatively simple, and efficient. We also show how this architecture is decoupled from (though dependent on) unicast routing, and is therefore easy to install in an internet that comprises multiple heterogeneous unicast routing algorithms.
Keywords: routing; multicast; core-based trees; spanning trees; IP; Internet

Christer Bohm, Per Lindgren, Lars Ramfelt, and Peter Sjödin, "Resource reservation in DTM," in 1st IEEE Symposium on Global Data Networking, (Cairo, Egypt), pp. 191-197, Dec. 1993.

Abstract: DTM is a fiber-optic network with bandwidth reservation and support for dynamic reallocation of bandwidth. DTM is designed for real-time multimedia applications and for high-speed computer communication. DTM provides a service with real-time guarantees: it allows reservation of bandwidth, and has constant delay between two nodes. DTM uses a novel medium-access technique and provides a multicast channel service. This paper describes how resources are reserved in DTM, and describes a DTM prototype implementation to demonstrate that the protocols can be implemented efficiently.

R. Braudes and S. Zabele, "Requirements for multicast protocols," Request for Comments (Informational) RFC 1458, Internet Engineering Task Force, May 1993.

Abstract: Multicast protocols have been developed over the past several years to address issues of group communication. Experience has demonstrated that current protocols do not address all of the requirements of multicast applications. This memo discusses some of these unresolved issues, and provides a high-level design for a new multicast transport protocol, group address and membership authority, and modifications to existing routing protocols.

S. Chuang, Jon Crowcroft, S. Hailes, M. Handley, N. Ismail, D. Lewis, and Ian Wakeman, "Multimedia application requirements for multicast communications services," in Proceedings of the International Networking Conference (INET), (San Francisco, California), pp. BFB-1 - BFB-9, Internet Society, Aug. 1993.

Abstract: Multimedia conferencing can be seen as a new way of distributing communication between several applications (rather than a single monolithic application) that often involves more than two end-systems. This can take advantage of multidestination communications services provided by multicast system based on host groups and the enhancement of routers to form special purpose forwarding paths to these groups. This is mainly so that the number of copies of packets sent over mesh topology wide area networks (X.25, IP, or CLNP, as well as SMDS and ATM based WANs) to group destinations may be reduced significantly over a simple replication at source, and so that the service interface is similar to that provided by multicast on networks with a physical broadcast technology (e.g., satellite and LANs). In this paper, we examine the snares and delusions that must be avoided when four different kinds of multicast applications uses a multicast network service, namely: shared window, packet digital audio, packet digital video and shared applications. This is based on the experience of a real (non-toy) system operating over international ISDN links in Europe, and the participation in the (configuration and use of) IETF Internet audio and video casts, to over 200 sites worldwide.
Keywords: Internet; MBONE; multicast; distributed systems; multimedia; conferencing; conference control

Jon Crowcroft and Paul Dourish, "Distributed active secure managed badges (DASMB)," Tech. Rep. RN/93/39, University College London, June 1993.

Abstract: The introduction of the active badge system at UCL raises several questions of security, some to do with authenticity, others to do with privacy. In this paper we present a novel secure protocol for distribution of badge location information, and explain the motivation behind such a scheme.
Keywords: multicast; active badge; authentication; privacy

Xing Chen and Jeremiah F. Hayes, "Access Control in Multicast Packet Switching," IEEE/ACM Transactions on Networking, vol. 1, Dec. 1993.

Abstract: The subject of the paper is the access control and performance of multicast packet switching in a broadband network environment. In terms of scheduling the transmission of the copies of the packet onto output ports, two basic service disciplines have been defined, 1) one-shot scheduling - all the copies transmitted in the same time slot and 2) call splitting - transmission over several time slots. As subcategories of call splitting, SS (strict-sense) specifies that each packet can send at most one copy to the destination per time slot; WS (wide-sense) does not carry this restriction. We propose a novel scheme, revision scheduling, which mitigates the HOL blocking effect by sequentially combining the one-shot scheduling and the call splitting disciplines. This paper introduces output contention resolution implementations, in the form of combinational logic circuits which are designed to resolve output contentions arising in each of the call scheduling disciplines, by incorporating a cyclic priority access policy. Also, a neural network based contention resolution algorithm is proposed to demonstrate the improvement of the optimal scheduling.

Gihwan Cho and Lindsay F. Marshall, "A multicast service for mobile computing," in 6th IEEE Workshop on Local and Metropolitan Area Networks, (San Diego, California), Oct. 1993.

Keywords: LAN; MAN; multicast; mobility

Pavel Curtis and David A. Nichols, "MUDs grow up: social virtual reality in the real world," unpublished memorandum, Jan. 1993.

Abstract: MUDs, or multi-user dungeons'' are programs that accept network connections from multiple simultaneous users and provide access to a shared database of rooms'', exits'' and other objects. Users browse and manipulate the database from inside'' the rooms, seeing only those objects that are in the same room and moving between rooms mostly via the exits that connect them. MUDs are thus a kind of virtual reality, an electronically-represented place'' that users can visit. - A recent list of Internet-accessible MUDs showed well over 200 advertised, running at sites all over the world. The busiest of these frequently host 50 to 100 simultaneous users. Clearly, these recreational MUDs are very popular systems. It seems clear to us that the simple technology of MUDs should also be useful in other, non-recreational applications. This paper presents our plans for exploring the implementation, applications, and implications of MUDs in work-oriented contexts. In the remainder of this introduction, we describe the capabilities of our own MUD server. We then describe the two major systems we are building as foci for our research. [The first system, Astro-VR, is a virtual meeting place for astronomers, with links to images and conference rooms for text and image presentations, recorded with questions for later replay. The second, Jupiter, includes multicast audio, with a separate audio channel for each room. The MUD is displayed as a graphical map. Video provides a sense of the activities of other users and for attending lectures. Real casual meeting areas will be integrated into the system. Jupiter can provide presence to telecommuters.
Keywords: MUD; virtual reality; packet audio

Steve Deering, Deborah Estrin, Dino Farinacci, and Van Jacobson, "Efficient support for sparse-group multicast routing," in 8th IEEE Workshop on Computer Communications, (Del Mar, California), IEEE, Oct. 1993.

Keywords: multicast; routing

Luca Delgrossi, Christian Halstrick, Dietmar Hehmann, Ralf Guido Herrtwich, Oliver Krone, Jochen Sandvoss, and Carsten Vogt, "Media scaling with HeiTS," IBM European Networking Center, Heidelberg, Germany, Mar. 1993.

Abstract: HeiTS, the Heidelberg Transport System, is a multimedia communication system for real-time delivery of digital audio and video data. HeiTS operates on top of guaranteed-performance networks that apply resource reservation techniques. To make HeiTS also work with networks for which no reservation scheme can be realized (e.g., Ethernet or existing internetworks), we implement an extension to HeiTS which performs media scaling at the transport level: the media encoding is modified according to the bandwidth available in the underlying networks. Both transparent and non-transparent scaling methods are examined. HeiTS lends itself to implement transparent temporal and spatial scaling of media streams. At the HeiTS interface, functions are provided which report some information on the available resource bandwidth to the application so that non-transparent scaling methods may be used, too. Both a continuous and discrete scaling solution for HeiTS are presented. The continuous solution uses feedback messages to adjust the data flow. The discrete solution also exploits the multipoint network connection mechanism of HeiTS. Whereas the first method is more flexible, the second technique is better suited for multicast scenarios.
Keywords: multicast; packet video; packet audio; MPEG; JPEG; media scaling; HeiTS

Luca Delgrossi, Christian Halstrick, Dietmer Hehmann, Ralf Guido Herrtwich, Oliver Krone, Jochen Sandvoss, and Carsten Vogt, "Media scaling for Audiovisual Communication with the Heidelberg Transport System," in Proc. of ACM Multimedia, pp. 99-104, June 1993.

Abstract: HeiTS, the Heidelberg Transport System, is a multimedia communication system for real time delivery of digital audio and video. HeiTS operates on top of guaranteed-performance networks that apply resource reservation techniques. To make HeiTS also work with networks for which no reservation scheme can be realized -for example, Ethernet or existing internetworks- we implement an extension to HeiTS which performs media scaling to the bandwidth available in the underlying networks. Both transparent and non-transparent scaling methods are examined. HeiTS lends itself to implement transparent temporal and spatial scaling of media streams. At the HeiTS interface, functions are provided which report information on the available resource bandwidth to the application so that non-transparent may be used too. Both a continuous and discrete scaling solution for HeiTS are presented. The continuous solution uses feedback messages to adjust the dataflow. The discrete solution also exploits the multimedia network connection mechanism of HeiTS. Whereas the first method is more flexible, the second technique is better suited for multicast scenarios. The combination of resource reservation and media scaling seems to particularly well-suited to meet the varying demands of distributed multimedia applications.
Keywords: multimedia; transparent scaling; HeiTS

Luca Delgrossi, Ralf Guido Herrtwich, Carsten Vogt, and Lars C. Wolf, "Reservation protocols for intervetworks: A comparison of ST-II and RSVP," in Proceedings of the 4th International Workshop on Network and Operating System Support for Digital Audio and Video, (Lancaster, U.K.), pp. 195-203, Lancaster University, Nov. 1993. Lecture Notes in Computer Science 846.

Abstract: Although efforts on reservation protocols for internetworks started quite some time ago, the research community is now becoming particularly active in this area, as proved by the high interest generated by protocols such as ST-II and RSVP. These two protocols, starting from different assumptions, have the common goal of providing guaranteed communication by reserving network bandwidth. This paper provides a short comparison of the two protocols. It describes and compares their mechanisms, focusing on the data forwarding, multicast, and quality of service aspects for multimedia communication. Rather than trying to decide which protocol is superior, we have identified the classes of applications which are better supported by one or the other protocol.
Keywords: multimedia; ST-II; RSVP

Walid Dabbus and Blaise Kiss, "A Reliable Multicast Protocol for a White Board Application," Tech. Rep. 2100, Institut National De Recherche En Informatique Et En Automatique (INRIA), Unite de Recherche INRIA Sophia-Antipolis Cedex France, Nov. 1993.

Abstract: This paper describes a proposed mechanism for a reliable multicast protocol working on top of unreliable network service and making efficient use of the underlying multicast facilities available on the Internet. The primary goal is to provide a reliable multicast transport for a multi-user shared workspace application which is commonly used with other interactive video or audio conferencing tools.
Keywords: reliable multicast; shared white board

Matthew Doar and Ian Leslie, "How bad is na\ive multicast routing?," in Proceedings of the Conference on Computer Communications (IEEE Infocom), vol. 1, (San Francisco, California), pp. 82-89 (1c.2), IEEE, March/April 1993.

Abstract: When the problem of routing multicast connections in networks has been previously considered, the emphasis has been on the source transmitting to a fixed set of destinations (the multicast group). There are some applications where destinations will join and leave the multicast group. Under these conditions, computing an optimal'' spanning tree after each modification may not be the best way to proceed. An alternative is to make modest alterations to an existing spanning tree to derive a new one. An extreme, though non-optimal, variation of this is to use minimal cost source to destination routing for each destination, effectively ignoring the existing multicast tree. We examine just how non-optimal these trees are in random general topology networks and conclude that they are worse by only a small factor. The factor is reduced still further if a hierarchy is imposed upon the random network to give a more realistic model.
Keywords: multicast; routing; Steiner tree; random network; random graphs

Noboru Endo, Takahiko Kozaki, Toshiya Ohuchi, and Shinobu Gohara, "A Shared Buffer Memory Switch for an ATM Exchange," IEEE Transactions on Communications, vol. 41, p. 10 pages, Jan. 1993.

Abstract: This paper proposes an Asynchronous Transfer Mode (ATM) switch architecture called a shared buffer memory switch, whose output cell buffers are shared among all the output ports of the switch. Buffer sharing can reduce the amount of hardware compared with that of a separated buffer memory switch. Moreover, modifying the memory control circuits of the switch makes the memory switch flexible enough to perform functions such as priority control and multicast. Experimental measurements and a discussion about the traffic characteristics of switch architecture are carried out to determine how much buffer memory will be reduced through buffer sharing under various traffic conditions and to roughly estimate how many buffers are needed for the switch to meet certain requirements. The resultant estimate shows that buffer sharing reduces the necessary buffer memory to less than 1/5 of what would otherwise be required, and the required buffer size is about 128 cells/output for a 32\times32 switch when considering bursty traffic conditions. LSI implementation is also discussed to show that a 32\times32 switch can be composed of about 12 chips mounted on one printed board.

Chip Elliott, "High-Quality Multimedia Conferencing Through a Long-Haul Packet Network," in Proc. of ACM Multimedia 93, (Anaheim, California), pp. 91-98, June 1993.

Abstract: Desktop multimedia may be just the first step toward long distance multimedia collaboration. This paper describes both the challenges and the opportunities of transmission high-fidelity multimedia data streams through long distance packet networks, in the context of practical experience with a worldwide videoconference system that operates over a new Internet with realtime transmission capabilities. This system conveys full-motion colour images and sound at near VCR quality and is currently in use both as research testbed and as a production videoconferencing system. It is deigned to support less common shared media such as realtime simulations or digitized maps. Its implementation incorporates a number of unusual features including the adaption of commercial codecs to a packetized network, use of ST-II network protocol for bandwidth reservation and multicasting, an experimental media negotiation scheme and a new sticky conference control protocol designed to minimize the effects of transient network failures and to scale up gracefully to large conferences.
Keywords: multimedia conferencing; ST-II; scalability

Alexandros Eleftheriadis, Sassan Pejhan, and Dimitris Anastassiou, "Multicast group address management and connection control for multi-party applications," submitted to IEEE/ACM Transactions on Networking, Apr. 1993.

Abstract: We describe and evaluate an architecture and associated protocols for managing multicast group addresses and performing connection control for multi-party applications. The paper assumes an underlying IP-based internetworking environment, but the results are shown to be applicable to a large class of network-layer protocols. A multicast address space partitioning scheme based on the network number is proposed, and its performance is characterized based on the call blocking probability and its scaling characteristics. A protocol is then developed which provides for dynamic allocation and release of multicast addresses, as well as connection control (i.e., maintaining connection state for a session). The protocol is independent of the address partitioning scheme, and hence is essentially applicable to any network layer; it is also shown to be robust and efficient; it is also shown to be robust and efficient. Finally, three independent port resolution mechanisms are described, namely address-based filtering, use of virtual port numbers, and a dedicated port resolution protocol. These mechanisms guarantee that a globally available (within the scope of the session) port number is used by all session participants. This paper concludes with a discussion of appropriate modifications to support non-IP based networks (e.g., OSI CLNP, ATM, etc.).
Keywords: multicast; port allocation; address allocation; connection control; address management; multi-party applications; conferencing; multimedia communications

Hans Eriksson, "MBone - the multicast backbone," in Proceedings of the International Networking Conference (INET), (San Francisco, California), pp. CCC-1 - CCC-5, Internet Society, Aug. 1993.

Abstract: MBone - the multicast backbone is technically a network of hosts running a multicast daemon. Functionally, MBone provides a multicasting facility to the Internet. This facility has been used to distribute audio and video from the IETF meetings, position data from a robot at the bottom of the Sea of Cortez, and a late night feature movie, just to mention a few items. The facility has also been the cause of severe Internet meltdowns due to different reasons. The network providers have viewed various opinions about what to do with multicasting as it is in the MBone, varying from forbidding to encourage pilot experiments. This paper will discuss the operational aspects of MBone, the symptoms that has surfaced and how it has evolved during the last year into a kind of semimaturity.
Keywords: Internet; MBONE; multicast; operational experience

Domenico Ferrari, "The Tenet approach to real-time communications and the Tenet real-time protocol suite," in Architecture and protocols for high-speed networks, (Wadern, Germany), p. 14, Dagstuhl Seminar, Sept. 1993.

Abstract: The Tenet approach to the design of real-time communication services is the foundation of one of the first protocol suites built to support multimedia and other real-time transmissions in integrated-services internetworks. The same approach is now being used in the design of another, more advanced protocol suite, based on a multicast guaranteed-performance channel abstraction. In this talk, the principles of the Tenet approach and the main features of the four protocols that constitute the first Tenet suite will be described. Some of the initial experiences with using the suite in some of the several packet-switching and cell-switching testbeds to which it is being ported will also be presented, and the most important characteristics of the second Tenet suite will be outlined.
Keywords: Tenet; real-time protocols

Bernd Heinrichs, "Towards a high performance and configurable multipeer transfer service," in Architecture and protocols for high-speed networks, (Wadern, Germany), p. 15, Dagstuhl Seminar, Sept. 1993.

Abstract: This paper highlights the need for sophisticated multicast mechanisms to be provided by transfer protocols in order to support group communication. This need becomes even more evident in the light of the special QOS requirements imposed by multi-media applications. Today's protocols do not provide the broad range of functionality required by these upcoming new applications. From a number of sample applications we derive functionality and performance requirements which have to be provided by transfer systems. Although various transport protocols are capable of providing some basic functionality used for multicast applications, they do not address all of the requirements of multicast applications. Therefore, some of the unsolved or very difficult issues for the provision of multicast services, like application specific error control, acknowledgement implosion, support of different grades of reliability, guarantee of different QOS requirements, scalability, etc., will be discussed. After comparing different ISO and Internet approaches the XTP multicast mechanism is illustrated in more detail. We show how some of the identified demands are met by this protocol. Furthermore, necessary enhancements are suggested. The usefulness of these enhancements is proved by simulations and measurements. Although XTP provides an interesting approach it is not possible to enhance the protocol by integrating all the desired functionality without changing the primary semantics of XTP. Thus, we specify our own approach, called AMTP (adaptive multipeer transfer protocol), a new multicast transfer protocol capable of providing high performance and flexibility.
Keywords: transport protocols; multicast; XTP

Bernd Heinrichs and Sabine Neuhauser, "Transfer-routing - a QOS-driven routing and multicast architecture," in 6th IEEE Workshop on Local and Metropolitan Area Networks, (San Diego, California), Oct. 1993.

Keywords: LAN; MAN; multicast; routing

Don Hoffman, Michael Speer, and Gerard Fernando, "Network support for dynamically scaled multimedia data streams," in Proceedings of the 4th International Workshop on Network and Operating System Support for Digital Audio and Video, (Lancaster, U.K.), pp. 251-262, Lancaster University, Nov. 1993. Lecture Notes in Computer Science 846.

Abstract: As multimedia applications such as video-on-demand and video conferencing become more common, the classes of systems and networks participating in these applications are becoming more diverse. Where several endpoints need to access the same video stream simultaneously, multicast protocols are often employed to reduce the duplication of network traffic across common links. Previous literature has discussed the concept that hierarchical media encodings may be used to achieve some form of stream scalability within a multicast network. This paper discusses the networking issues associated with encoding hierarchical streams and mapping them to a multimedia transport service interface.
Keywords: multimedia; transport protocol; hierarchical coding; packet video; scaling; RTP

Andrzej Jajszczyk, "A Class of Directional-coupler-Based Photonic Switching Networks," IEEE Transactions on Communications, vol. 41, p. 10 pages, Apr. 1993.

Abstract: A class of photonic switching networks composed of directional couplers is proposed. These networks require only two switching stages containing active elements. Both point-to-point and multicast architectures are presented. Various characteristics of the proposed networks are compared with those of the networks previously known, including: insertion loss, SNR, number of crossovers, and number of active elements.

Van Jacobson, Steve McCanne, and Sally Floyd, "A conferencing architecture for light-weight sessions," Nov. 1993. MICE seminar series (transparencies).

Keywords: conference control; vat; packet video; packet audio; session; application layer; multicast; sd; light-weight session; wb; LWS

Winfried Kalfa, "Receiver initiated multicast in the ST-II protocol," in Architecture and protocols for high-speed networks, (Wadern, Germany), p. 16, Dagstuhl Seminar, Sept. 1993.

Abstract: In the specification of ST-II only the source of the multicast stream is able to connect a new receiver to the stream. This needs an alternate connection to inform the source about a new receiver. A better way consists in the use of the ST-II protocol itself. Two versions are presented by addition of new features to the protocol. The arising problem of authorization is discussed.
Keywords: ST-II; signaling

P. T. Kirstein, M. J. Handley, and M. A. Sasse, "Piloting of multimedia integrated communications for European researchers (MICE)," in Proceedings of the International Networking Conference (INET), (San Francisco, California), pp. DCA-1 - DCA-12, Internet Society, Aug. 1993.

Abstract: The paper describes multimedia conferencing and describes the facilities currently available. It discusses briefly the activities which require standardization and the progress in this direction to date. It gives an overview of the MICE project, which utilizes existing conferencing rooms, workstations, codecs and software, and existing network infrastructure, to offer researchers conferencing facilities within Europe, as well as a link to the US. The goals of the project, its achievements to date, and problems encountered are discussed in detail. Finally, we outline forthcoming activities.
Keywords: Internet; multimedia; conferencing; packet video; MICE; RTP; conference control; packet audio; multicast; H.261

H. T. Kung, Robert Morris, Thomas Charuhas, and Dong Lin, "Use of Link-by-Link Flow Control in Maximizing ATM Network Performance - Simulation Results," in Appeared in Proc. IEEE Hot Interconnects Symposium, '93, p. 12 pages, Aug. 1993.

Abstract: Simulations have been performed to verify the effectiveness of using link-by-link flow controlled virtual channels for maximizing ATM network performance. A simulator which accurately reflects the real hardware design of a flow controlled ATM switch is used. The switch is currently under joint development by BNR and Harvard. The simulation results clearly demonstrate that the flow control mechanism is able to provide sufficiently rapid feedback to allow a network to adapt to load changes and maximize its performance. The simulations also so that, when compared to VCs using other traffic management approaches, flow controlled virtual circuits are efficient in terms of buffer usage and in point-to-multipoint multicast implementations.
Keywords: ATM ATM, traffic management ATM, flow control flow control, link-by-link flow control, N23 Scheme ATM, multicast

J. Kaniyil, Y. Onozato, and W. D. Zhong, "A Copy Network with Shared Buffers for Large Multicast ATM switches," in Conference Record of the International Conference on Communications (ICC), vol. 2, (Geneva), pp. 722-726, 1993.

Abstract: This paper proposes a new architecture for the copy network which is an integral part of multicast ATM switches. The new architecture makes use of the property that the Broadcast BanyanNetwork (BBN) is non-blocking if the active inputs are cyclically concentrated and the outputs are monotone. In the new architecture, by employing a token ring reservation scheme, the outputs of the copy net. are reserved before multic. cell is replicated.
Keywords: ATM; buffer management; multicast; Banyan network; nonblocking; performance analysis; architecture

Vachaspathi P. Kompella, Joseph C. Pasquale, and George C. Polyzos, "Multicast Routing for Multimedia Communication," IEEE/ACM Transactions on Networking, vol. 1, pp. 286-292, June 1993.

Abstract: We present heuristics for multicast tree construction for communication that depends on: (i) bounded end-to-end delay along the paths from source to each destination, and (ii) minimum cost of the multicast tree, where edge cost and edge delay can be independent metrics. This problem of computing such a constrained multicast tree is NP-complete. We show that the heuristics demonstrate good average case behavior in terms of cost, as determined through simulations on a large number of graphs.
Keywords: routing; multicast; Steiner tree

Oivind Kure and Ingvild Sorteberg, "XTP over ATM," Computer Networks and ISDN Systems, vol. 26, pp. 253-267, Nov. 1993.

Abstract: This paper discusses some of the issues involved in mapping the Express transfer protocol (XTP) over the ATM (Asynchronous Transfer mode) network technology. Both ATM and XTP are designed to faciltitate high bandwidth transfers. ATM offers virtual channels that can be utilized to carry XTP frames without any encapsulation. The added benefit is the ability to offer different Quality of Service with the XTP channels. The largest problem area is the mapping of XTP signalling on the signalling used in ATM. There is a mismatch in mechanisms that will result in inefficiency in the implementations. Some of the mechanisms in XTP seem to be optimized for shared medium technologies like Ethernet and FDDI. In our opinion this needs to be changed in future versions of the protocol.
Annotation: XTP multicasting requires the setting up of n one-to-many communications channels for n participants, as every multicast participant must receive the control messages from every other participant.

M. Frans Kaashoek, Robbert Van~Renesse, Hans Van~Staveren, and Andrew S. Tanenbaum, "FLIP: an internetwork protocol for supporting distributed systems," ACM Transactions on Computer Systems, vol. 11, pp. 73-106, Feb. 1993.

Abstract: Most modern network protocols give adequate support for traditional applications such as file transfer and remote login. Distributed applications, however, have different requirements (e.g., efficient at-most-once remote procedure call even in the face of processor failures). Instead of using ad hoc protocols to meet each of the new requirements, we have designed a new protocol, call the Fast Local Internet Protocol (FLIP), that provides a clean and simple integrated approach to these new requirements. FLIP is an unreliable message protocol that provides both point-to-point communication and multicast communication, and requires almost no network management. Furthermore, by using FLIP we have simplified higher-level protocols such as remote procedure call and group communication, and enhanced support for process migration and security. A prototype implementation of FLIP has been built as part of the new kernel for the Amoeba distributed operating system, and is in daily use. Measurements of its performance are presented.
Keywords: network protocols; FLIP; IP; RPC; protocol implementation; multicast; local area networks
Annotation: 64-bit addresses, randomly allocated with ARP-like address resolution; security through do-not-travel bits

Bernd Lamparter, Otto Böhrer, Wolfgang Effelsberg, and Volker Turau, "Adaptable forward error correction for multimedia data streams," Tech. Rep. TR-93-009, Praktische Informatik IV, Universität Mannheim, 1993.

Abstract: The error handling method in traditional communication protocols is error detection and retransmission. This method is inappropriate for distributed multimedia systems for two reasons: It introduces variable delay unacceptable for isochronous streams, and it is very inefficient and difficult to use in the multicast environment typical for many multimedia applications. We propose AdFEC, an adaptable Forward Error Correction scheme based on binary polynomial algebra. It produces an adaptable amount of redundancy allowing different packet types to be protected according to their importance. The scheme was implemented in the framework of the XMovie project and proved to be very efficient.

Chin Tau Lea, "A Multicast Broadband Packet Switch," IEEE Transactions on Communications, vol. 41, p. 10 pages, Apr. 1993.

Abstract: Historically, multicast is only needed for a small portion of all services provided by a network. The demand for multicast in a future ATM broadband packet network is still an unknown quantity. If this demand is small, many methods for multicast implementation can become an overkill. Therefore, the challenge we face in designing a multicast packet switch for the future broadband ATM network is not just good performance - cost efficiency is perhaps more important. A multicast broadband packet switch architecture is proposed in this paper. It has the following attractive features: (1) little extra cost compared with a unicast switch, (2) fast packet duplication, and (3) easy addition and deletion of calling parties. Simulation study of this multicast system is also presented to verify its performance.

Xiaola Lin and Lionel M. Ni, "Multicast Communication in Multicomputer Networks," IEEE Transactions on Parallel and Distributed Systems, vol. 4, Oct. 1993.

Abstract: Efficient routing of messages is a key to the performance of multicomputers. Multicast communication refers to the delivery of the same message from a source node to an arbitrary number of destination nodes. While multicast communication is highly demanded in many applications, most of the existing multicomputers do not directly support this service; rather it is indirectly supported by multiple one-to-one or broadcast communications, which result in more network traffic and a waste of system resources. In this paper, we study routing evaluation criteria for multicast communication under different switching technologies. Multicast communication in multicomputers is formulated as a graph theoretical problem. Depending on the evaluation criteria and switching technologies, we study three optimal multicast communication problems, which are equivalent to the finding of the following three subgraphs: optimal multicast path, optimal multicast cycle, and minimal Steiner tree, where the interconnection of a multicomputer defines a host graph. We will show that all these optimization problems are NP-complete for the popular 2D-mesh and hypercube host graphs. Heuristic multicast algorithms for these routing problems are proposed.

Danny Mitzel, Deborah Estrin, Scott Shenker, and Lixia Zhang, "An architectural comparison of ST-II and RSVP," unpublished memorandum, Sept. 1993.

Abstract: Many real-time applications in an Integrated Services Packet Network (ISPN) require Quality of Service (QoS) guarantees from the network, and support for multipoint-to-multipoint communications. One component of this architecture is the reservation protocol, which is responsible for requesting allocation and release of network resources along the data distribution path to ensure QoS requirements are met. Resulting network utilization and efficiency depends to a great extent on the reservation protocol's service model and dynamic response. This paper presents a comparison of two reservation protocols, ST-II and RSVP, in terms of their ability to support applications anticipated to be in common use in future Integrated Services Networks. Our main objective is in determining the effect the service model presented to the end-user has on scaling behavior of the protocol; this affects the size and number of groups that can be supported. We use simulations to determine the network-wide resource requirements for each protocol to support a number of application communication styles, across a range of group sizes and membership distributions. We also present a comparative analysis of the protocol features to accommodate network and group membership dynamics.
Keywords: multicast; ST-II; RSVP; resource reservation; scaling; admission control; simulation

John Moy, "Multicast routing extensions for OSPF," in Proceedings of the International Networking Conference (INET), (San Francisco, California), pp. BCC-1 - BCC-7, Internet Society, Aug. 1993.

Abstract: The OSPF protocol has been extended to handle the routing of IP multicast datagrams. This has applications in many areas, such as voice and video conferencing, distributed databases, games and simulations. This paper describes the characteristics of multicast routing in OSPF, together with a description of protocol mechanisms and a brief analysis of protocol performance. Experience with the protocol to date is also presented.
Keywords: Internet; MOSPF; OSPF; multicast; Dijkstra; routing; link-state routing; IGMP; MBONE

Yoram Ofek, "Multicast and semi-{FIFO protocols over virtual rings in the MetaNet," in 8th IEEE Workshop on Computer Communications, (Del Mar, California), IEEE, Oct. 1993.

Keywords: multicast; LAN; MetaNet

T. Pusateri, "IP multicast over token-ring local area networks," Request for Comments (Proposed Standard) RFC 1469, Internet Engineering Task Force, June 1993.

Abstract: This document specifies a method for the transmission of IP multicast datagrams over Token-Ring Local Area Networks. Although an interim solution has emerged and is currently being used, it is the intention of this document to specify a more efficient means of transmission using an assigned Token-Ring functional address.

Bala Rajagopalan, "Consensus and control in wide-area group communication," unpublished memorandum, Nov. 1993.

Abstract: Agreement on and control of group membership are basic, but inadequately addressed problems in wide-area group communication. These problems arise in supporting services such as multicast transport, multiparty teleconferencing, secure multicasting, etc. In this paper, we consider a symmetric group communication environment, where each member could be a sender as well as a receiver of multicast messages, and address the problem of maintaining consistent group membership information at each member and controlling the manner in which group membership changes, using distributed protocols. A dynamic network environment is assumed, where process and network failures may occur unpredictably and message delivery is unreliable. Unlike prior work in this area, our protocols are general and flexible; they tolerate partitioning network failures and do not require consistent network-level routing information being present at each network node.
Keywords: conference control; distributed systems
Annotation: presented at 28th IETF, Houston, Texas

Nachum Shacham, "Heterogeneous multicast over ATM," in 8th IEEE Workshop on Computer Communications, (Del Mar, California), IEEE, Oct. 1993.

Keywords: ATM; multicast

T. E. Stern and Song Jiang, "Multicast-multihop networks: connectivity and performance," in 8th IEEE Workshop on Computer Communications, (Del Mar, California), IEEE, Oct. 1993.

Keywords: optical networks; multicast

Andre Schiper and Aleta M. Ricciardi, "Virtually-Synchronous Communication Based on a Weak Failure Suspector," Tech. Rep. TR93-1339, Cornell University, Computer Science Department, Apr. 1993.

Abstract: Failure detectors (or, more accurately, Failure Suspectors - FS) appear to be a fundamental service upon which to build fault-tolerant, distributed applications. This paper shows that a FS with very weak semantics (i.e. that delivers failure and recovery information in no specific order) suffices to implement virtually-synchronous communication (VSC) in an asynchronous system subject to process crash failures and network partitions. The VSC paradigm is particularly useful in asynchronous systems and greatly simplifies building fault-tolerant applications that mask failures by replicating processes. We suggest a three-component architecture to implement virtually-synchronous communication : 1) at the lowest level, the FS component; on top of it, 2a) a component that defines new views, and 2b) a component that reliably multicasts messages within a view. The issues covered in this paper also lead to a better understanding of the various membership service semantics proposed in recent literature.

Masaru Takesue, "A Family of Parallel Prefix Algorithms Embedded in Networks," IEEE Transactions on Parallel and Distributed Systems, vol. 4, Oct. 1993.

Abstract: This paper presents a family of algorithms for producing, from (v_0,v_1,\ldots,v_n-1), all initial prefixes x_iv_0Tv_1T\ldots Tv_i (i 0, 1, \ldots,n-1) in parallel in interconnection networks such as the omega network and the hypercube, where T is an associative binary operator. Each algorithm can be embedded in the switches and interconnections of the network, and can be executed in O((log_2 r+1) \log constructed by using an rxr switch, and that parallelism within as well as among individual switches is exploited. The objective of these algorithms is to attain a communication pattern that fits the topology of the network. One type of network can be made equivalent to, or can be embedded in, another type of network, so a family of algorithms can be derived from one basic algorithm. In the basic algorithm, every processor p_i upward multicasts v_i to processors p_k (k=i+1, i+2, \ldots, n-1). En route to p_i, v_j(j=0,1,\ldots i-1) are combined in the switches to produce the (i-1)-th initial prefix x_i-1 that is received by p_i, which can then compute the i-th initial prefix x_ix_i-1Tv_i.

Thierry Turletti, "H.261 software codec for videoconferencing over the Internet," Rapports de Recherche 1834, Institut National de Recherche en Informatique et en Automatique (INRIA), Sophia-Antipolis, France, Jan. 1993.

Abstract: This report describes a low-bandwidth videoconferencing application on the Internet using tbe IP multicast extensions and the User Datagram Protocol (UDP) transport protocol. The video coder-decoder is a software implementation of tbe CCITT recommendation H.261 originally developped for the Integrated Services Digital Network (ISDN). Until now, H.261 codecs have been implemented in hardware. We find that the mean output rate of the coder is less than 30 kb/s, thus making videoconferencing applications possible over low-speed networks such as the Internet. After a brief overview of the different data compression techniques and a description of the recommendation H.261, we describe in more details IVS, our videoconferencing application which is freely available in the public domain.
Keywords: H.261; data compression; Internet; video conferencing; UDP; IP multicast; codec; implementation

Jonathan S. Turner, "A Practical Version of Lee's Multicast Switch Architecture," IEEE Transactions on Communications, vol. 41, p. 4 pages, Aug. 1993.

Abstract: This paper describes several improvements to Lee's multicast switch architecture. Our improvements make Lee's architecture practical, allowing it to achieve maximum network throughput under worst-case conditions and drastically reducing the amount of memory required for addressing of multicast cells. These improvements allow multicast to be added to a 256 port switch with 150 Mb/s links at a cost of about two additional chips per port.

Dinesh C. Verma, "Routing reserved bandwidth multi-point connections," in SIGCOMM Symposium on Communications Architectures and Protocols (Deepinder P. Sidhu, ed.), (San Francisco, California), pp. 96-105, ACM, Sept. 1993. also in \em Computer Communication Review 23 (4), Oct. 1992.

Abstract: Some important classes of multi-point bandwidth-intensive applications like video-conferencing with mixing and the distributed classroom can be characterized as consisting of a broadcast from a source node to several destination nodes, and point-to-point flows from the destination nodes to the source node. Determining a tree in an arbitrary mesh network which satisfies the bandwidth constraints and minimizes the cost of reserved bandwidth is an NP-hard problem. In this paper, we look at some heuristics that can be used to solve the problem of routing these multi-point connections. The heuristics are based on finding the capacity-constrained minimum cost tree which minimizes the cost of bandwidth reserved for point-to-point communication from destinations to the source, and weights are assigned to minimize the number of extra nodes in the tree which increase the cost of bandwidth reserved from the source to the destination. A theoretical bound on the performance of some of the heuristics, as well as simulation results comparing their performance to that of the optimum solution are presented. The results are encouraging, the heuristics find a tree with a cost within 2% of the optimum on average, and with a cost within 10% of the optimum in those cases when the heuristic fails to find the optimum tree.
Keywords: routing; multicast; spanning tree; optimization

Ian Wakeman, "Packetised Video: Options for interaction between the User, the Network and the Codec," Computer Journal, vol. 36, Feb. 1993.

Abstract: In this paper we analyse the requirements that the user and a packet network have of compressed video. From these, we produce a synthesis of the characteristics of an ideal video compression coding. Using this dialectic, we the examine the currently available compression schemes and determine which is closest to the ideal.
Keywords: packet video; video coding; multicast; H.261; MPEG; subband coding; vector quantization; HDTV; rate control

Zheng Wang and Jon Crowcroft, "A unified framework for multicast forwarding," in Proceedings of the 4th International Workshop on Network and Operating System Support for Digital Audio and Video, (Lancaster, U.K.), pp. 252-258, Lancaster University, Nov. 1993. Lecture Notes in Computer Science 846.

Abstract: This paper examines the issues in multicast from the perspective of implementation and integration. A framework for multicast forwarding is presented, which separates multicast forwarding from multicast routing. This framework provides a unified interface with which different multicast algorithms, host membership algorithms and resource management algorithms can be seamlessly integrated.
Keywords: multicast; routing; forwarding; router; IP

Raj Yavatkar and Leelavinas Manoj, "Optimistic Strategies for Large-Scale Dissemination of Multimedia Information," in Proceedings of ACM Multimedia '93, (Anaheim, California), Aug. 1993.

Abstract: We are investigating alternative transport protocol strategies for realizing large scale dissemination services across a wide area network. Communication requirements of such applications are distinct from those based on conventional client-server interactions. Conventional flow and error control methods based on the \em retransmissions-with-timeout paradigm are not appropriate for such applications. Instead, we are interested in using optimistic flow and error control strategies that take into account application-specific error tolerance and media rates of multimedia applications. This paper describes transport level policies that use a combination of redundant transmissions, rate-based flow control, and selective feedback from receivers. A simulation-based performance evaluation demonstrates that relatively simple techniques succeed well in meeting the QOS requirements of a multimedia multicast and in scaling to hundreds of recipients.
Keywords: multicast; multimedia; reliable multicast; flow control

Lixia Zhang, Bob Braden, Deborah Estrin, Shai Herzog, and Sugih Jamin, "Resource reservation protocol (RSVP) - version 1 functional specification," Internet Draft, Xerox PARC, Oct. 1993. Work in progress.

Abstract: This memo describes version 1 of RSVP, a resource reservation setup protocol designed for an integrated services Internet. RSVP provides receiver-initiated setup of resource reservations for multicast or unicast data flows, with good scaling and robustness properties.
Keywords: RSVP; resource reservation; call setup; signaling

Lixia Zhang, Stephen Deering, Deborah Estrin, Scott Shenker, and Daniel Zappala, "RSVP: a new resource ReSerVation protocol," IEEE Network, vol. 7, pp. 8-18, Sept. 1993.

Abstract: Novel design features lead to an Internet protocol that is flexible and scalable.
Keywords: resource reservation; RSVP; multicast; IP

Lixia Zhang, Steve Deering, Deborah Estrin, Scott Shenker, and Daniel Zappala, "RSVP: a new resource reservation protocol," in Proceedings of the International Networking Conference (INET), (San Francisco, California), pp. BCB-1, Internet Society, Aug. 1993.

Abstract: This talk will present the design of a resource reservation protocol, RSVP, that supports both unicast and multicast applications, even when the number of sources and/or receivers is very large. Several novel features in the RSVP design lead to the unique flexibility and scalability of the protocol. RSVP is receiver-oriented, in that the receiver of the data flow is responsible for the initiation of the resource reservation; this allows RSVP to accomodate heterogeneous receivers in a multicast group. RSVP provides several reservation styles that allow applications to specify how reservations for the same multicast group should be aggregated at the intermediate switches; this results in more efficient utilization of network resources. Finally, RSVP uses soft-state'' in the switches, enabling it to gracefully support dynamic membership changes and automatically adapt to routing changes.
Keywords: Internet; resource reservation; multimedia; multicast; RSVP

Lixia Zhang, "RSVP: a new reservation protocol," in 8th IEEE Workshop on Computer Communications, (Del Mar, California), IEEE, Oct. 1993.

Abstract: This paper presents the design of a resource reservation protocol, RSVP, that supports both unicast and multicast applications, even when the number of sourcs and/or receivers is very large. Several novel features in the RSVP design lead to the unique flexibility and scalability of the protocol. RSVP is receiver-oriented, in that the receiver of the data flow is responsible for the initiation of the resource reservation; this allows RSVP to accomodate heterogeneous receivers in a multicast group. RSVP provides several reservation styles that allow applications to specify how reservations for the same multicast group should be aggregated at the intermediate switches; this results in more efficient utilization of network resources. Finally, RSVP uses soft-state'' in the switches, enabling it to gracefully support dynamic membership changes and automatically adapt to routing changes.
Keywords: RSVP; resource reservation; signaling; multicast

Wen De Zhong and Jaidev Kaniyil, "A copy network with shared buffers for large-scale multicast ATM switching," IEEE/ACM Transactions on Networking, vol. 1, pp. 157-165, Apr. 1993.

Abstract: This paper proposes a new architecture for the copy network which is an integral part of multicast ATM switches. The new architecture makes use of the property that the broadcast Banyan network (BBN) is nonblocking if the active inputs are cyclically concentrated and the outputs are monotone. In the new architecture, by employing a token ring reservation scheme, the outputs of the copy network are reserved before a multicast cell is replicated. By the new copy principle, the number of copies requested by a multicast call is not limited by the size of the copy network so that very large multicast switches can be configured in a modular fashion. The sequence of cells is preserved in the new structure. Though physically separated, buffers within the copy network are completely shared, so that the throughput can reach 100%, and the cell delay and the cell loss probability can be made to be very small. The cell delay is estimated analytically and by computer simulation, and the results of both are found to agree with each other. The relationship between the cell loss probability under various traffic parameters and buffer sizes is studied by computer simulation.
Keywords: ATM; multicast; fast packet switches

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