Multiplex communications – Data flow congestion prevention or control
Reexamination Certificate
1998-07-22
2002-08-27
Ton, Dang (Department: 2661)
Multiplex communications
Data flow congestion prevention or control
C370S395100, C370S401000
Reexamination Certificate
active
06442135
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to a method and apparatus for monitoring, policing and billing of the transmission of data packet on a communications network. More specifically, this invention provides the monitoring, policing and billing in networks with timely forwarding and delivery of data packets to their destination nodes. Consequently, the end-to-end performance parameters, such as, loss, delay and jitter, are predictable, and therefore, it is possible to measure them. Consequently, such measurements are used in the monitoring, policing and billing.
The proliferation of high-speed communications links, fast processors, and affordable, multimedia-ready personal computers brings about the need for wide area networks that can carry real time data, like telephony and video. However, the end-to-end transport requirements and the ability to measure the actual performance of real-time multimedia applications present a major challenge that cannot be solved satisfactorily by current a synchronous networking technologies.
Monitoring, policing and billing are possible today only over circuit-switching networks, which are still the main carrier for real-time traffic, are designed for telephony service and cannot be easily enhanced to support multiple services or carry multimedia traffic. Its synchronous byte switching enables circuit-switching networks to transport data streams at constant rates with little delay or jitter. However, since circuit-switching networks allocate resources exclusively for individual connections, they suffer from low utilization under bursty traffic. Moreover, it is difficult to dynamically allocate circuits of widely different capacities, which makes it a challenge to support multimedia traffic. Finally, the synchronous byte switching of SONET, which embodies the Synchronous Digital Hierarchy (SDH), requires increasingly more precise clock synchronization as the lines speed increases [Balla et al., “SONET: Now It's The Standard Optical Network”, IEEE Communications Magazine, Vol. 29 No. 3, March 1989, pages 8-15] [M. Schwartz, “Telecommunication Networks: Protocols, Modeling, and Analysis”, Addison Wesley, Reading Mass., 1987].
Packet switching networks like IP (Internet Protocol)-based Internet and Intranets [see, for example, A.Tannebaum, “Computer Networks” (3rd Ed) Prentice Hall, 1996] are not designed for doing monitoring, policing and billing.
In order to facilitate the capability for monitoring, policing and billing some enhancements were proposed for P networks. Such methods for providing different services under packet switching fall under the general title of Quality of Service (QoS). Prior art in QoS can be divided into two parts: (1) traffic shaping with local timing without deadline scheduling, for example [M. G. H. Katevenis, “Fast Switching And Fair Control Of Congested Flow In Broadband Networks”, IEEE Journal on Selected Areas in Communications, SAC-5(8):1315-1326, Oct. 1987; Demers et al., “Analysis and Simulation Of A Fair Queuing Algorithm”, ACM Computer Communication Review (SIGCOMM'89), pages 3-12, 1989; S. J. Golestani, “Congestion-Free Communication In High-Speed Packet Networks”, IEEE Transcripts on Communications, COM-39(12):1802-1812, December 1991; Parekh et al., “A Generalized Processor Sharing Approach To Flow Control—The Multiple Node Case”, IEEEIACM T. on Networking, 2(2):137-150, 1994], and (2) traffic shaping with deadline scheduling, for example [Ferrari et al., “A Scheme For Real-Time Channel Establishment In Wide-Area Networks”, IEEE Journal on Selected Areas in Communication, SAC-8(4):368-379, Apr. 1990; Kandlur et al., “Real Time Communication In Multi-Hop Networks”, IEEE Trans. on Parallel and Distributed Systems, Vol. 5, No. 10, pp. 1044-1056, 1994]. Both of these approaches rely on manipulation of local queues by each router with little coordination with other routers. The Weighted Fair Queuing (WFQ), which typifies these approaches, is based on cyclical servicing of the output port queues where the service level of a specific class of packets is determined by the amount of time its queue is served each cycle [Demers et al., “Analysis and Simulation Of A Fair Queuing Algorithm”, ACM Computer Communication Review (SIGCOMM'89), pages 3-12, 1989]. These approaches have inherent limitations when used to transport real-time streams. When traffic shaping without deadline scheduling is configured to operate at high utilization with no loss, the delay and jitter are inversely proportional to the connection bandwidth, which means that low rate connections may experience large delay and jitter inside the network. In traffic shaping with deadline scheduling the delay and jitter are controlled at the expense of possible congestion and loss.
The real-time transport protocol (RTP) [H. Schultzrinne et. al, RTP: A Transport Protocol for Real-Time Applications, IETF Request for Comment RFC1889, January 1996] is a method for encapsulating time-sensitive data packets and attaching to the data time related information like time stamps and packet sequence number. RTP is currenty the accepted method for transporting real time streams over IP intemetworks and packet audio/video telephony based on ITU-T H.323.
One approach to an optical network that uses synchronization was introduced in the synchronous optical hypergraph [Y. Ofek, “The Topology, Algorithms And Analysis Of A Synchronous Optical Hypergraph Architecture”, Ph.D. Dissertation, Electrical Engineering Department, University of Illinois at Urbana, Report No. UIUCDCS-R-87-1343, May 1987], which also relates to how to integrate packet telephony using synchronization [Y. Ofek, “Integration Of Voice Communication On A Synchronous Optical Hypergraph”, INFOCOM'88, 1988]. In the synchronous optical hypergraph, the forwarding is performed over hyper-edges, which are passive optical stars. In [Li et al., “Pseudo-Isochronous Cell Switching In ATM Networks”, IEEE INFOCOM'94, pages 428-437, 1994; Li et al., “Time-Driven Priority: Flow Control For Real-Time Heterogeneous Internetworking”, IEEE INFOCOM'96, 1996] the synchronous optical hypergraph idea was applied to networks with an arbitrary topology and with point-to-point links. The two papers [Li et al., “Pseudo-Isochronous Cell Switching In ATM Networks”, IEEE INFOCOM'94, pages 428-437, 1994; Li et al., “Time-Driven Priority: Flow Control For Real-Time Heterogeneous Internetworking”, IEEE INFOCOM'96, 1996] provide an abstract (high level) description of what is called “RISC-like forwarding”, in which a packet is forwarded, with little if any details, one hop every time frame in a manner similar to the execution of instructions in a Reduced Instruction Set Computer (RISC) machine [Patterson et al., “Computer Architecture: A Quantitative Approach”, Morgan Kaufman Publishers, San Francisco, 1990].
In U.S. Pat. No. 5,455,701, Eng et al. discloses an apparatus for controlling a high-speed optical switching system with pipeline controller for switch control. In U.S. Pat. No. 5,418,779 Yemini et al. disclose a switched network architecture with common time reference. The time reference is used in order to determine the time in which multiplicity of nodes can transmit simultaneously over one predefined routing tree to one destination. At every time instance the multiplicity of nodes are transmitting to different single destination node.
SUMMARY OF THE INVENTION
This invention discloses a method for monitoring and policing the packet traffic in a packet switching network where the switches maintain a common time reference.
This invention enables designated points inside the network to ascertain the level of packet traffic in predefine time intervals, and control the flow of packets and bring it back to predetermined levels in cases where the traffic volume exceeds predetermined levels.
The information collected by the designated points facilitates billing fo
Nguyen Brian
Sitrick & Sitrick
Synchrodyne Networks, Inc.
Ton Dang
LandOfFree
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