waashk/acm huggingface dataset:
dynamics of ip traffic: a study of the role of variability and the impact of control using the _ns-2_-simulator to experiment with different aspects of user- or session-behaviors and network configurations and focusing on the qualitative aspects of a wavelet-based scaling analysis, we present a systematic investigation into how and why variability and feedback- control contribute to the intriguing scaling properties observed in actual internet traces (as our benchmark data, we use measured internet traffic from an isp). we illustrate how variability of both user aspects and network environments (i) causes self-similar scaling behavior over large time scales, (ii) determines a more or less pronounced change in scaling behavior around a specific time scale, and (iii) sets the stage for the emergence of surprisingly rich scaling dynamics over small time scales; i.e., multifractal scaling. moreover, our scaling analyses indicate whether or not open-loop controls such as udp or closed-loop controls such as tcp impact the local or small-scale behavior of the traffic and how they contribute to the observed multifractal nature of measured internet traffic. in fact, our findings suggest an initial physical explanation for why measured internet traffic over small time scales is highly complex and suggest novel ways for detecting and identifying, for example, performance bottlenecks.this paper focuses on the qualitative aspects of a wavelet-based scaling analysis rather than on the quantitative use for which it was originally designed. we demonstrate how the presented techniques can be used for analyzing a wide range of different kinds of network-related measurements in ways that were not previously feasible. we show that scaling analysis has the ability to extract relevant information about the time-scale dynamics of internet traffic, thereby, we hope, making these techniques available to a larger segment of the networking research community. anja feldmann anna c. gilbert polly huang walter willinger
an experiment to improve operand addressing  mcode is a high-level language, stack machine designed to support strongly- typed, pascal-based languages with a variety of data types in a modular programming environment. the instruction set, constructed for efficiency and extensibility, is based on an analysis of 120,000 lines of pascal programs. the design was compared for efficiency with the instruction sets of the digital equipment pdp-11 and vax by examining the generated code from the same compiler for all three machines. in addition, the original design choices were tested by analyzing the generated code from 19,000 lines of starmod programs. as a result of this iterative experiment, we have summarized our observations in an efficient reorganization of the vax's addressing modes.  robert p. cook nitin donde
a hop by hop rate-based congestion control scheme  the flow/congestion control scheme of tcp is based on the sliding window mechanism. as we demonstrate in this paper, the performance of this and other similar end-to- end flow control schemes deteriorates as networks move to the gigabit range. this has been the motivation for our search for a new flow and congestion control scheme. in this paper, we propose as an alternative, a hop- by-hop rate-based mechanism for congestion control. due to the increasing sophistication in switch architectures, to provide "quality of service" guarantees for real-time as well as bursty data traffic, the implementation of hop-by-hop controls has become relatively inexpensive. a cost-effective implementation of the proposed scheme for a multi-gigabit packet switch is described in [2]. in this paper, we present results of a simulation study comparing the performance of this hop-by-hop flow control scheme to two end- to-end flow control schemes. the results indicate that the proposed scheme displays stable behavior for a wide range of traffic conditions and diverse network topologies. more importantly, the performance of the scheme, measured in terms of the average number of occupied buffers, the end-to-end throughput, the network delay, and the link utilization at the bottleneck, is better than that of the end-to-end control schemes studied here. these results present a convincing case against popular myths about hop- by-hop control mechanisms.  partho p. mishra hemant kanakia
construction of a validated simulator for performance prediction of decnet- based computer networks  predicting important performance parameters of computer networks, recognizing potential bottlenecks, comparing design alternatives are factors of decisive importance in building complex computer networks. in this respect, computer aided simulation has proved to be a very effective design tool in a number of practical applications. it is shown by the example of the mosaic modeling system how a simulator applicable on a broad basis could be adapted to the specific characteristics of a class of existing computer networks.  the class of computer networks chosen for modeling is based on decnet communication software. modeling concentrates mainly on the decnet protocols and their hierarchies. the paper indicates the adaptations necessary to adjust the mosaic kernel system adequately to decnet computer networks and summarizes the results of a rather extensive validation for the modeling system, comprising calibration and accuracy establishment, which has been carried out successfully.  bernd wolfinger max muhlhauser
a resilient communication structure for local area netowrks  reliable communication is crucial to the correct functioning of distributed systems. we propose a multi-ring communication structure and a reconfiguration algorithm that tolerate multiple link failures before the network divides into more than one partition. in case of partitioning, each partition is reconfigured to allow communication among the sites within the partition. the algorithm handles recovery of links and merges partitions once links become operational again. the algorithm itself is fault-tolerant, and it is fully distributed and does not require global knowledge about the status of the network at any one site.  amr el abbadi thomas rauchle
publish/subscribe in a mobile enviroment  a publish/subscribe system dynamically routes and delivers events from sources to interested users, and is an extremely useful communication service when it is not clear in advance who needs what information. in this paper we discuss how a publish/subscribe system can be extended to operate in a mobile environment, where events can be generated by moving sensors or users, and subscribers can request delivery at handheld and/or mobile devices. we describe how the publish/subscribe system itself can be distributed across multiple (possibly mobile) computers to distribute load, and how the system can be replicated to cope with failures, message loss, and disconnections.  yongqiang huang hector garcia- molina
accelerating shared virtual memory via general-purpose network interface support  clusters of symmetric multiprocessors (smps) are important platforms for high- performance computing. with the success of hardware cache- coherent distributed shared memory (dsm), a lot of effort has also been made to support the coherent shared-address-space programming model in software on clusters. much research has been done in fast communication on clusters and in protocols for supporting software shared memory across them. however, the performance of software virtual memory (svm) is still far from that achieved on hardware dsm systems. the goal of this paper is to improve the performance of svm on system area network clusters by considering communication and protocol layer interactions. we first examine what are the important communication system bottlenecks that stand in the way of improving parallel performance of svm clusters; in particular, which parameters of the communication architecture are most important to improve further relative to processor speed, which ones are already adequate on modern systems for most applications, and how will this change with technology in the future. we find that the most important communication subsystem cost to improve is the overhead of generating and delivery interrupts for asynchronous protocol processing. then we proceed to show, that by providing simple and general support for asynchronous message handling in a commodity network interface (ni) and by altering svm protocols appropriately, protocol activity can be decoupled from asynchronous message handling, and the need for interrupts or polling can be eliminated. the ni mechanisms needed are generic, not svm- dependent. we prototype the mechanisms and such a synchronous home-based lrc protocol, called genima (general-purpose network interface support for shared memory abstractions), on a cluster of smps with a programmable ni. we find that the performance improvements are substantial, bringing performance on a small-scale smp cluster much closer to that of hardware- coherent shared memory for many applications, and we show the value of each of the mechanisms in different applications.  angelos bilas dongming jiang jaswinder pal singh
a multi-microprocessor architecture with hardware support for communication and scheduling  we describe a multiprocessor system that attempts to enhance the system performance by incorporating into its architecture a number of key operating system concepts. in particular:  \\--- the scheduling and synchronization of concurrent activities are built in at the hardware level,  \\--- the interprocess communication functions are performed in hardware, and,  \\--- a coupling between the scheduling and communication functions is provided which allows efficient implementation of parallel systems that is precluded when the scheduling and communication functions are realized in software.  sudhir r. ahuja abhaya asthana
the transport layer: tutorial and survey  transport layer protocols provide for end-to-end communication between two or more hosts. this paper presents a tutorial on transport layer concepts and terminology, and a survey of transport layer services and protocols. the transport layer protocol tcp is used as a reference point, and compared and contrasted with nineteen other protocols designed over the past two decades. the service and protocol features of twelve of the most important protocols are summarized in both text and tables.  sami iren paul d. amer phillip t. conrad
acknowledgment procedures at radio link control level in gprs in this paper, we investigate the acknowledgment procedures used at radio link control level in general packet radio service (gprs). the gprs is a new gsm service, which is currently being standardized by etsi for gsm phase 2+ and it provides packet switched data services over gsm network resources. the role of acknowledgment procedures is to assure the delivery of packets on gprs radio interface. this paper gives a brief description of gprs radio interface with a special attention to the radio link control and medium access control (rlc/mac) layer procedures. particularly, the acknowledgment parameters and operations are described and their performance is evaluated. the delay introduced by acknowledgment procedures is studied analytically. in order to ameliorate the performance of rlc acknowledgment mechanism, we propose and describe a new additional hybrid fec/arq mechanism, which can operate with the current one. the purpose of new mechanism is to decrease the number of control blocks used for rlc acknowledgment mechanism and thus reduces the delay requested for a packet delivery. after presenting the channel models used, we evaluate by simulation the performance of acknowledgment procedures presented in etsi specifications and the proposed one over a stationary channel model and over a noisy wireless channel model affected by burst of errors.
a high speed transport protocol for datagram/virtual circuit networks  we present a design and preliminary analysis of an end- to-end transport protocol that is capable of high throughput consistent with the evolving wideband physical networks based on fiber optic transmission lines and high capacity switches. unlike the current transport protocols in which changes in control state information are exchanged between the two communicating entities only when some significant event occurs, our protocol exchanges relevant and full state information periodically, routinely and frequently. we show that this results in reducing the complexity of protocol processing by removing many of the procedures required to recover from the inadequacies of the network such as bit-errors, packet loss, out of sequence packets and makes it more amenable to parallel processing. also, to increase channel utilization in the presence of high speed, long latency networks, and to support datagrams, we propose an efficient implementation of selective repeat method of error control used in our protocol. thus, we utilize small extra bandwidth to simplify protocol processing; a trade-off that appears proper since electronic speeds for protocol processing are far slower than fiber transmission rates. our preliminary estimates indicate that 20,000 packets/second can be handled in a completely software implementation on a 10 mip microprocessor using 8% of its cycles.  k. k. sabnani a. n. netravali
quality of service based routing: a performance perspective recent studies provide evidence that quality of service (qos) routing can provide increased network utilization compared to routing that is not sensitive to qos requirements of traffic. however, there are still strong concerns about the increased cost of qos routing, both in terms of more complex and frequent computations and increased routing protocol overhead. the main goals of this paper are to study these two cost components, and propose solutions that achieve good routing performance with reduced processing cost. first, we identify the parameters that determine the protocol traffic overhead, namely (a) policy for triggering updates, (b) sensitivity of this policy, and (c) clamp down timers that limit the rate of updates. using simulation, we study the relative significance of these factors and investigate the relationship between routing performance and the amount of update traffic. in addition, we explore a range of design options to reduce the processing cost of qos routing algorithms, and study their effect on routing performance. based on the conclusions of these studies, we develop extensions to the basic qos routing, that can achieve good routing performance with limited update generation rates. the paper also addresses the impact on the results of a number of secondary factors such as topology, high level admission control, and characteristics of network traffic. george apostolopoulos roch guerin sanjay kamat satish k. tripathi
a modified cdma/prma medium access control protocol for integrated services in leo satellite systems  the goal of this paper is the design of a multiservice mac (medium access control) layer able to use efficiently the radio channel within a leo (low earth orbit) constellation. after presenting the context of the problem, a set of capabilities within mac layer, which provide communications able to support various applications such as video, data and voice, are defined. a new mac protocol, based on the cdma/prma one, is proposed in the context of leo systems. compared with the initial cdma/prma protocol, the proposed modifications do significantly increase the efficiency of mac layer in leo context. a cac (connection admission control) function is introduced, and several control users traffic methods are presented and studied by simulation.  abbas ibrahim samir tohme
design constraints in the construction of a truly distributed operating system (abstract only)  distributed computing will be viewed from three levels. first, from possible hardware configurations, where emphasis will be placed on loosely coupled systems interconnected with high speed networks (hsn). second, from the operating system (os) level where five fundamental additions to existing uniprocessor oss are required. they include the creation of a message-based interprocess communication facility, a communication manager, an extended file manager, a resource manager, and an extended user interface. the third and final view of truly distributed oss will be from the applications level. how the user views the logical system, and automatic versus manual control of computational granularity will be discussed.  p. tobin maginnis
adaptive interpretation as a means of exploiting complex instruction sets  in this paper we concentrate on the effect of instruction set architecture on the performance potential of a computer system. these issues are key in considerations of what instruction set is most appropriate for the support of high level languages on general purpose machines. two possible approaches are so called complex instruction sets, such as those of the vax and iapx 432, and the "reduced" instruction set of the risc i [2] microcomputer, which is expected to have performance similar to that of a vax 11-780.  we propose a method of instruction set interpretation that takes advantage of the architectural features of complex instruction sets. these methods have been simulated executing real programs and in the case of the vax instruction set have resulted in a typical improvement of a factor of two, assuming the same cycle time as the vax 11-780. the techniques presented exploit the context available in a complex instruction and retain this information for use in subsequent execution of that instruction. since this context is available only within a single instruction, low level instruction sets cannot benefit from this technique. in this sense the reduced instruction set machines as implemented in risc are at their architectural limits, while complex instruction sets such as the vax are far from theirs. for these reasons, complex instruction sets can have a significantly greater performance potential than a risc instruction set for a given technology.  richard l. norton jacob a. abraham
performance of the expressnet with voice/data traffic  in the past few years, local area networks have come into widespread use for the interconnection of computers. together with the trend towards digital transmission in voice telephony, this has spurred interest in integrated voice/data networks. the expressnet, an implicit-token round-robin scheme using unidirectional busses, achieves high performance even at bandwidths of 100 mb/s. other features that make the protocol attractive for voice/data traffic are bounded delays and priorities. the latter is achieved by devoting alternate rounds to one or the other of the two traffic types. by the use of accurate simulation, the performance of the expressnet with voice/data traffic is characterized. it is shown that the expressnet satisfies the real-time constraints of voice traffic adequately even at bandwidths of 100 mb/s. data traffic is able to effectively utilize bandwidth unused by voice traffic. the trade-offs in the alternating round priority mechanism are quantified. loss of voice samples under overload is shown to occur regularly in small, frequent clips, subjectively preferable to irregular clips. in a comparison of the expressnet, the contention-based ethernet and the round-robin token bus protocols, the two round-robin protocols are found to perform better than the ethernet under heavy load owing to the more deterministic mode of operation. the comparison of the two round-robin protocols highlights the importance of minimizing scheduling overhead at high bandwidths.  timothy a. gonsalves fouad a. tobagi
distributed fault-tolerance for large multiprocessor systems  techniques for dealing with hardware failures in very large networks of distributed processing elements are presented. a concept known as distributed fault-tolerance is introduced. a model of a large multiprocessor system is developed and techniques, based on this model, are given by which each processing element can correctly diagnose failures in all other processing elements in the system. the effect of varying system interconnection structures upon the extent and efficiency of the diagnosis process is discussed, and illustrated with an example of an actual system.  finally, extensions to the model, which render it more realistic, are given and a modified version of the diagnosis procedure is presented which operates under this model.  j. g. kuhl s. m. reddy
security in a networked environment networking allows multiple users to share data, information, software, and hardware. in addition, a network can centralize the management of a large base of connected processing units often configured to provide one location for coordinating security, backup and control. security is the means to limit damage to data and to prevent user access to unauthorized information. the question of maintaining adequate security provisions across heterogenous platforms presents new security challenges for the network administrator. computer crimes are on the rise. these crimes range from eavesdropping confidential information to physicial damage of equipments that information is stored. some reasons of the increase in computer crimes include that there are more computers in use, there are more networks, and pcs can now access larger mainframe databases. cleopas o. angaye
determination of the registration point for location update by dynamic programming in pcs location management is important to effectively keep track of mobile terminals with reduced signal flows and database queries. even though dynamic location management strategies are known to show good performance, we in this paper consider the static location management strategy which is easy to implement. a system with single home location register and pointer forwarding is assumed. a mobile terminal is assumed to have memory to store the ids of visitor location registers (vlrs) each of which has the forwarding pointer to identify its current location. to obtain the registration point which minimizes the database access and signaling cost from the current time to the time of power-off probabilistic dynamic programming formulation is presented. a selective pointer forwarding scheme is proposed which is based on one-step dynamic programming. the proposed location update scheme determines the least cost temporary vlr which point forwards the latest location of the mobile. the computational results show that the proposed scheme outperforms is-41, pure pointer forwarding, and one-step pointer forwarding at the expense of small storage and a few computations at the mobile terminals. chae y. lee seon g. chang
fast and scalable wireless handoffs in supports of mobile internet audio  future internetworks will include large numbers of portable devices moving among small wireless cells. we propose a hierarchical mobility management scheme for such networks. our scheme exploits locality in user mobility to restrict handoff processing to the vicinity of a mobile node. it thus reduces handoff latency and the load on the internetwork. our design is based on the internet protocol (ip) and is compatible with the mobile ip standard. we also present experimental results for the lowest level of the hierarchy. we implemented our local handoff mechanism on unix-based portable computers and base stations, and evaluated its performance on a wavelan network. these experiments show that our handoffs are fast enough to avoid noticeable disruptions in interactive audio traffic. for example, our handoff protocol completes less than 10 milliseconds after a mobile node initiates it. our mechanism also recovers from packet losses suffered during the transition from one cell to another. this work helps extend internet telephony and teleconferencing to mobile devices that communicate over wireless networks.  ramon caceres venkata n. padmanabhan