A description is given of NoW, a method for virtual channel connection (VCC) establishment in asynchronous transfer mode (ATM) networks in which a source sends the VCC establishment request message on the channel it wishes to establish (i.e. no signaling channel is used) and can then immediately send data over the channel. A key point of departure from other methods is that some identifiers for virtual channels include the address of the VCC destination endpoint. Analytical and simulation results that provide evidence of the applicability of the method are described. A software implementation for the Blanca/Xunet 2 environment is also described. Under the present implementation, VCC establishment takes 330 mu s per intermediate node. Design modifications to the Xunet 2 hardware that allow VCC establishment (and teardown) to be performed in the time it takes a single cell to flow through an intermediate node are described.>

The authors present mechanisms for congestion control of data traffic in high-speed wide area networks. The network model assumes reservation of resources based on average requirements. The key ideas involve separation of different sources of network congestion, short-term bursts and medium-term load, and using separate mechanisms to address them. Thus, dynamic time window (DTW) admission control is proposed as a mechanism to limit traffic burstiness from sources as a function of the medium-term load on the system, while a new fairness criterion for short-term congestion (Pulse) is proposed as a mechanism for dealing with fair scheduling by switches of short-term bursts. The model of the network is presented. The DTW and Pulse mechanisms are discussed. A detailed analytical and simulation study is presented for static time-windows and various scheduling algorithms. Preliminary results on DTW are discussed.>

We present a feedback congestion control method, Dynamic Time Windows, for use in high speed wide area networks based on controlling source variance. It is part of the two-level integrated congestion control system introduced in our earlier work[1].The method consists of a packet admission control system and a feedback system to dynamically control source burstiness. Source throughput is not modulated as with traditional packet windows, allowing system throughput to remain high while avoiding congestion. Furthermore, the admission control bounds congestion times in the network, allowing feedback to be effective in the face of large bandwidth delay products.The basic control mechanisms are analogs to traditional packet windows applied to controlling time windows - a new mechanism which allows switches to modulate source variances. The proposed system is simulated, and the results reported and analyzed. Enhancements to the basic system are also proposed and analyzed.We wish to stress that the system described here is the second level of a two-level congestion control. Previous work[1] concentrated on the switch queueing mechanism, Pulse, while this work is a detailed examination of the feedback system used to adjust time windows to changing network load.

A token ring local area network, the parallelring, is introduced. The ability to concurrently support multiple communication paths on a single loop in an efficient and fair manner differentiates the parallelring from earlier ring architectures. This is accomplished by using a message destination removal scheme and, hence, allowing more than one station to transmit a variable-length frame at a time. Simulation studies show that the parallelring exhibits better performance in terms of throughput-delay characteristics than the other token rings. In addition, a priority scheme is used in the parallelring to provide messages of different time constraints with different media access priorities so that it can support media access fairness and real-time services. In the parallelring, error detection and recovery are completely decentralized.>

Article Free Access Share on Simultaneous analysis of flow and error control strategies with congestion-dependent errors Authors: Amarnath Mukherjee Computer Sciences Department, University of Wisconsin - Madison Computer Sciences Department, University of Wisconsin - MadisonView Profile , Lawrence H. Landweber Computer Sciences Department, University of Wisconsin - Madison Computer Sciences Department, University of Wisconsin - MadisonView Profile , John C. Strikwerda Computer Sciences Department, University of Wisconsin - Madison Computer Sciences Department, University of Wisconsin - MadisonView Profile Authors Info & Claims SIGMETRICS '90: Proceedings of the 1990 ACM SIGMETRICS conference on Measurement and modeling of computer systemsApril 1990Pages 86–95https://doi.org/10.1145/98457.98510Published:01 April 1990Publication History 5citation300DownloadsMetricsTotal Citations5Total Downloads300Last 12 Months14Last 6 weeks1 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

We present an evaluation of retransmission strategies over local area networks. Expressions are derived for the expectation and the variance of the transmission time of the go-back-n and the selective repeat protocols in the presence of errors. These are compared to the expressions for blast with full retransmission on error (BFRE) derived by Zwaenepoel [Zwa 85]. We conclude that go-back-n performs almost as well as selective repeat and is very much simpler to implement while BFRE is stable only for a limited range of messages sizes and error rates. We also present a variant of BFRE which optimally checkpoints the transmission of a large message. This is shown to overcome the instability of ordinary BFRE. It has a simple state machine and seems to take full advantage of the low error rates of local area networks. We further investigate go-back-n by generalizing the analysis to an upper layer transport protocol, which is likely to encounter among other things, variable delays due to protocol overhead, multiple connections, process switches and operating system scheduling priorities.

article Free Access Share on Optimizing bulk data transfer performance: a packet train model Authors: C. Song Univ. of Wisconsin, Madison Univ. of Wisconsin, MadisonView Profile , L. H. Landweber Univ. of Wisconsin, Madison Univ. of Wisconsin, MadisonView Profile Authors Info & Claims ACM SIGCOMM Computer Communication ReviewVolume 18Issue 4August 1988 pp 134–145https://doi.org/10.1145/52325.52339Published:01 August 1988Publication History 8citation670DownloadsMetricsTotal Citations8Total Downloads670Last 12 Months38Last 6 weeks3 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

A new methodology for specifying and implementing communication protocols is presented. This methodology is based on a formalism called “Real-Time Asynchronous Grammars” (RTAG), which uses a syntax similar to that of attribute grammars to specify allowable message sequences. In addition RTAG provides mechanisms for specifying data-dependent protocol activities, real-time constraints, and concurrent activities within a protocol entity. RTAG encourages a top-down approach to protocol design that can be of significant benefit in expressing and reasoning about highly complex protocols. As an example, an RTAG specification is given for part of the Class 4 ISO Transport Protocol (TP-4).

An important function of CSNET is to simplify communication by electronic mail. To this end, a Name Server facility is being implemented, which will free users from having to understand the complexities of inter-network mail addressing. The Name Server includes a database and accessing software on a central Service Host machine, as well as programs and data structures on CSNET member hosts. We describe the architecture of the Name Server and discuss considerations that lead to its design.

Petri nets have been extensively studied because of their suitabi1ity as models for asynchronous computing. Despite this effort, the mathematical properties of Petri nets are not very well understood. In this paper, we investigate two important special types of Petri nets, the conflict free and the persistent nets, the former being a proper subset of the latter. Our results completely characterize the sets of reachable markings attainable by such nets. Reachability sets of persistent nets are shown to be semilinear. A stronger result is obtained for conflict free nets which results in an exponential time algorithm for deciding boundedness of such nets. The best known upper bound for deciding boundedness of arbitrary nets is Ackerrnann's function. We conclude with a proof that all reachability sets of Petri nets may be realized with a minimal amount of non-persistence.

A program scheme which models straight-line code admitting structured variables such as arrays, lists, and queues is considered. A set of expressions is associated with a program reflecting the input-output transformations. A basic set of axioms is given and program equivalence is defined in terms of expression equivalence. Program transformations are then defined such that two programs are equivalent if and only if one program can be transformed to the other via the transformations. An application of these results to code optimization is then discussed.

It is proven that complexity classes of abstract measures of complexity need not be recursively enumerable, However, the complement of each class is shown to be r.e. The results are extended to complexity classes determined by partial functions, and the properties of these classes are investigated. Properties of effective enumerations of complexity classes are studied. For each measure another measure with the same complexity classes is constructed such that almost every class admits an effective enumeration of efficient devices. Finally complexity classes are shown not to be closed under intersection.

It is proven that complexity classes of abstract measures of complexity need not be recursively enumerable. However, the complement of each class is r.e.

Let be a relational system whereby D is a nonempty set and P1 is an m1-ary relation on D. With we associate the (weak) monadic second-order theory consisting of the first-order predicate calculus with individual variables ranging over D; monadic predicate variables ranging over (finite) subsets of D; monadic predicate quantifiers; and constants corresponding to P1, P2, …. We will often use ambiguously to mean also the set of true sentences of .