waashk/acm huggingface dataset:
transport protocol processing at gbps rates  this paper proposes an architecture for accomplishing transport protocol processing at gbps rates. the limitations of currently used transport protocols have been analyzed extensively in recent literature. several benchmark studies have established the achievable throughput of iso tp4 and tcp to be in the low mbps range; several new protocols and implementation techniques have been proposed to achieve 100 mbps and higher throughput rates. we briefly review some of these protocols and establish the need for a radically different approach to meet our objective. an estimate of the aggregate processing power required for gbps throughput is developed. it is proposed that a cost effective and practical solution to the processing requirements could be based on a multi-processor system. the opportunities for parallel processing in a typical transport protocol are examined. several alternate parallel processing approaches are examined and arguments are advanced for selecting a favored approach. a corresponding parallel processing architecture is described. data structures used to preserve packet ordering and techniques for reducing contention in a multi-processing environment are discussed. an implementation methodology for conventional transport protocols (e.g. tp4) is outlined. some suggestions are made for improving efficiency by making modifications to the protocol that do not compromise functionality. the performance achievable with this modified architecture is analyzed and some suggestions for further work are presented.  n. jain m. schawrtz t. bashkow
arpanet performance tuning techniques  as part of its operation and maintenance of the arpanet for the past twelve years, bbn has been asked to investigate a number of cases of degradation in network performance. this presentation discusses the practical methods and tools used to uncover and correct the causes of these service problems. a basic iterative method of hypothesis generation, experimental data gathering, and analysis is described. emphasis is placed on the need for experienced network analysts to direct the performance investigation and for the availability of network programmers to provide special purpose modifications to the network node software in order to probe the causes of the traffic patterns under observation. many typical sources of performance problems are described, a detailed list of the tools used by the analyst are given, and a list of basic techniques provided. throughout the presentation specific examples from actual arpanet performance studies are used to illustrate the points made.  james g. herman
ergonomics of wearable computers  wearable computers represent a new and exciting area for technology development, with a host of issues relating to display, power and processing still to be resolved. wearable computers also present a new challenge to the field of ergonomics; not only is the technology distinct, but the manner in which the technology is to be used and the relationship between user and computer have changed in a dramatic fashion. in this paper, we concentrate on some traditional ergonomics concerns and examine how these issues can be addressed in the light of wearable computers.  chris baber james knight d. haniff l. cooper
trading packet headers for packet processing in high speed networks, packet processing is relatively expensive while bandwidth is cheap. thus it pays to add information to packet headers to make packet processing easier. while this is an old idea, we describe several specific new mechanisms based on this principle. we describe a new technique, _source hashing_, which can provide _o_(1) lookup costs at the data link, routing, and transport layers. source hashing is especially powerful when combined with the old idea of a _flow id_; the flow identifier allows packet processing information to be cached, and source hashing allows efficient cache lookups. unlike virtual circuit identifiers (vcis), source hashing does not require a round trip delay for set up. in an experiment with the bsd packet filter implementation, we found that adding a flow id and a source hash improved packet processing costs by a factor of 7. we also found a 45% improvement when we conducted a similar experiment with ip packet forwarding. we also describe two other new techniques: _threaded indices_, which allows fast vci-like lookups for datagram protocols like ip; and a _data manipulation layer_, which compiles out all the information needed for integrated layer processing into an easily accessible portion of each packet. girish p. chandranmenon george varghese
amp: a highly parallel atomic multicast protocol  this paper deals with the problem of reliable group communication for distributed applications, in the context of the reliable broadcast class of protocols. an atomic multicast protocol for token passing lans is presented. the actual implementation is on an 8802/4 token-bus, although it is applicable to 8802/5 token-rings and the fddi fibre-optic network.  the simplicity and efficiency of reliable broadcast protocols may be considerably improved, if the system fault model is restricted or convenient architectures are used. fail-controlled communication components are used here to build an efficient reliable multicast protocol on top of the exposed mac interface of a vlsi lan controller. the architecture is built on standard lans, in view of taking advantage of the availability of communications hardware and the possibility of coexistence with standard stations, in the same network.  the service offered allows transparent multicasting inside logical groups, which are dynamically created and updated. the primitive is highly parallel and provides atomic agreement and consistent delivery order, respecting logical precedence. these features are an important contribution for the implementation of high performance distributed computing systems.  p. veríssimo l. rodrigues m. baptista
on power-law relationships of the internet topology despite the apparent randomness of the internet, we discover some surprisingly simple power-laws of the internet topology. these power-laws hold for three snapshots of the internet, between november 1997 and december 1998, despite a 45% growth of its size during that period. we show that our power-laws fit the real data very well resulting in correlation coefficients of 96% or higher.our observations provide a novel perspective of the structure of the internet. the power-laws describe concisely skewed distributions of graph properties such as the node outdegree. in addition, these power-laws can be used to estimate important parameters such as the average neighborhood size, and facilitate the design and the performance analysis of protocols. furthermore, we can use them to generate and select realistic topologies for simulation purposes. michalis faloutsos petros faloutsos christos faloutsos
user-space protocols deliver high performance to applications on a low-cost gb/s lan  two important questions in high-speed networking are firstly, how to provide gbit/s networking at low cost and secondly, how to provide a flexible low- level network interface so that applications can control their data from the instant it arrives.  we describe some work that addresses both of these questions. the jetstream gbit/s lan is an experimental, low-cost network interface that provides the services required by delay-sensitive traffic as well as meeting the performance needs of current applications. jetstream is a combination of traditional shared- medium lan technology and more recent atm cell- and switch-based technology.  jetstream frames contain a channel identifier so that the network driver can immediately associate an incoming frame with its application. we have developed such a driver that enables applications to control how their data should be managed without the need to first move the data into the application's address space. consequently, applications can elect to read just a part of a frame and then instruct the driver to move the remainder directly to its destination. individual channels can elect to receive frames that have failed their crc, while applications can specify frame-drop policies on a per- channel basis.  measured results show that both kernel- and user-space protocols can achieve very good throughput: applications using both tcp and our own reliable byte- stream protocol have demonstrated throughputs in excess of 200 mbit/s. the benefits of running protocols in user-space are well known- the drawback has often been a severe penalty in the performance achieved. in this paper we show that it is possible to have the best of both worlds.  aled edwards greg watson john lumley david banks costas calamvokis c. dalton
floor acquisition multiple access (fama) for packet-radio networks a family of medium access control protocols for single-channel packet radio networks is specified and analyzed. these protocols are based on a new channel access discipline called floor acquisition multiple access (fama), which consists of both carrier sensing and a collision-avoidance dialogue between a source and the intended receiver of a packet. control of the channel (the floor) is assigned to at most one station in the network at any given time, and this station is guaranteed to be able to transmit one or more data packets to different destinations with no collision with transmissions from other stations. the minimum length needed in control packets to acquire the floor is specified as a function of the channel propagation time. the medium access collision avoidance (maca) protocol proposed by karn and variants of csma based on collision avoidance are shown to be variants of fama protocols when control packets last long enough compared to the channel propagation delay. the throughput of fama protocols is analyzed and compared with the throughput of non-persistent csma. this analysis shows that using carrier sensing as an integral part of the floor acquisition strategy provides the benefits of maca in the presence of hidden terminals, and can provide a throughput comparable to, or better than, that of non-persistent csma when no hidden terminals exist. chane l. fullmer j. j. garcia-luna-aceves
an energy consumption model for performance analysis of routing protocols for mobile ad hoc networks a mobile ad hoc network (or manet) is a group of mobile, wireless nodes which cooperatively form a network independent of any fixed infrastructure or centralized administration. in particular, a manet has no base stations: a node communicates directly with nodes within wireless range and indirectly with all other nodes using a dynamically-computed, multi- hop route via the other nodes of the manet. simulation and experimental results are combined to show that energy and bandwidth are substantively different metrics and that resource utilization in manet routing protocols is not fully addressed by bandwidth-centric analysis. this report presents a model for evaluating the energy consumption behavior of a mobile ad hoc network. the model was used to examine the energy consumption of two well- known manet routing protocols. energy-aware performance analysis is shown to provide new insights into costly protocol behaviors and suggests opportunities for improvement at the protocol and link layers. laura marie feeney
the wakeup problem in synchronous broadcast systems (extended abstract)  this paper studies the differences between two levels of synchronization in a distributed broadcast system (or a multiple access channel). in the globally synchronous model, all processors have access to a global clock. in the locally synchronous model, processors have local clocks ticking at the same rate, but each clock starts individually, when the processor wakes up.  we consider the fundamental problem of waking up all of n processors of a completely connected broadcast system. some processors wake up spontaneously, while others have to be woken up. only wake processors can send messages; a sleeping processor is woken up upon hearing a message. the processors hear a message in a given round if and only if exactly one processor sends a message in that round. our goal is to wake up all processors as fast as possible in the worst case, assuming an adversary controls which processors wake up and when. we analyze the problem in both the globally synchronous and locally synchronous models, with or without the assumption that n is known to the processors. we propose randomized and deterministic algorithms for the problem, as well as lower bounds in some of the cases. these bounds establish a gap between the globally synchronous and locally synchronous models.  leszek gasieniec andrzej pelc david peleg
performance modelling of the orwell basic access mechanism  orwell is a high speed slotted ring. its protocol uses destination release of the slots. because of this the carried load can be much larger than the transmission rate. a new analytical model of the orwell basic access mechanism is presented in this paper. the model shows to be accurate and usable over a wide range of parameters. the performance analysis of the orwell basic access mechanism is presented.  m. zafirovic i. g. niemegeers
supercomputers: challenges to designers and users  session overview: the objective of this panel is to present and discuss issues concerned with the development and use of present and future supercomputers for large-scale scientific and engineering problems. presentations by each of four panelists will be followed by a question and answer session with audience participation. below some brief background information is given on the subject matter along with a list of several topics that will be addressed. also included is a bibliography to help the reader become acquainted with the many aspects of the session theme.  myron ginsberg
the dash prototype: implementation and performance  the fundamental premise behind the dash project is that it is feasible to build large-scale shared-memory multiprocessors with hardware cache coherence. while paper studies and software simulators are useful for understanding many high-level design trade-offs, prototypes are essential to ensure that no critical details are overlooked. a prototype provides convincing evidence of the feasibility of the design allows one to accurately estimate both the hardware and the complexity cost of various features, and provides a platform for studying real workloads. a 16-processor prototype of the dash multiprocessor has been operational for the last six months. in this paper, the hardware overhead of directory-based cache coherence in the prototype is examined. we also discuss the performance of the system, and the speedups obtained by parallel applications running on the prototype. using a sophisticated hardware performance monitor, we characterize the effectiveness of coherent caches and the relationship between an application's reference behavior and its speedup.  daniel lenoski james laudon truman joe david nakahira luis stevens anoop gupta john hennessy
vertical handoffs in wireless overlay networks  no single wireless network technology simultaneously provides a low latency, high bandwidth, wide area data service to a large number of mobile users. wireless overlay networks \-- a hierarchical structure of room-size, building- size, and wide area data networks -- solve the problem of providing network connectivity to a large number of mobile users in an efficient and scalable way. the specific topology of cells and the wide variety of network technologies that comprise wireless overlay networks present new problems that have not been encountered in previous cellular handoff systems. we have implemented a vertical handoff system that allows users to roam between cells in wireless overlay networks. our goal is to provide a user with the best possible connectivity for as long as possible with a minimum of disruption during handoff. results of our initial implementation show that the handoff latency is bounded by the discovery time, the amount of time before the mobile host discovers that it has moved into or out of a new wireless overlay. this discovery time is measured in seconds: large enough to disrupt reliable transport protocols such as tcp and introduce significant disruptions in continuous multimedia transmission. to efficiently support applications that cannot tolerate these disruptions, we present enhancements to the basic scheme that significantly reduce the discovery time without assuming any knowledge about specific channel characteristics. for handoffs between room-size and building-size overlays, these enhancements lead to a best-case handoff latency of approximately 170 ms with a 1.5% overhead in terms of network resources. for handoffs between building-size and wide-area data networks, the best-case handoff latency is approximately 800 ms with a similarly low overhead.  mark stemm randy h. katz
achieving bounded fairness for multicast and tcp traffic in the internet there is an urgent need for effective multicast congestion control algorithms which enable reasonably fair share of network resources between multicast and unicast tcp traffic under the current internet infrastructure. in this paper, we propose a quantitative definition of a type of bounded fairness between multicast and unicast best-effort traffic, termed "essentially fair". we also propose a window-based random listening algorithm (rla) for multicast congestion control. the algorithm is proven to be essentially fair to tcp connections under a restricted topology with equal round-trip times and with phase effects eliminated. the algorithm is also fair to multiple multicast sessions. this paper provides the theoretical proofs and some simulation results to demonstrate that the rla achieves good performance under various network topologies. these include the performance of a generalization of the rla algorithm for topologies with different round-trip times. huayan amy wang mischa schwartz
pruning algorithms for multicast flow control  multicast flow (congestion) control establishes a data rate for a multicast session based on prevailing bandwidth availability given other network traffic. this rate is dictated by the sender's path to the slowest receiver. this level of performance, however, may not be in the best interest for the multicast group as a whole. a pruning algorithm is then used to identify and remove some slow members so that the performance is acceptable for the whole group. this paper discusses the conceptual issues with pruning, and proposes practical algorithms for pruning. the crux of the problem is to achieve a balance between speed and accuracy, because increased accuracy tends to require monitoring for a longer time and using more global information. we evaluate and compare different strategies using both simulation and measurement of real implementations.  dah ming chiu miriam kadansky joe provino joseph wesley haifeng zhu
hardware support for interprocess communication  in recent years there has been increasing interest in message-based operating systems, particularly in distributed environments. such systems consist of a small message-passing kernel supporting a collection of system server processes that provide such services as resource management, file service, and global communications. for such an architecture to be practical, it is essential that basic messages be fast, since they often replace what would be a simple procedure call or "kernel call" in a more traditional system. careful study of several operating systems shows that the limiting factor, especially for small messages, is typically not network bandwidth but processing overhead. therefore, we propose using a special- purpose coprocessor to support message passing. our research has two parts: first, we partitioned an actual message-based operating system into communication and computation parts interacting through shared queues and measured its performance on a multiprocessor. second, we designed hardware support in the form of a special- purpose smart bus and smart shared memory and demonstrated the benefits of these components through analytical modeling using generalized timed petri nets. our analysis shows good agreement with the experimental results and indicates that substantial benefits may be obtained from both the partitioning of the software and the addition of a small amount of special-purpose hardware.  u. ramachandran m. solomon m. vernon
instruction translation for an experimental s/390 processor the ibm s/390 architecture is a complex architecture, which has grown over a long period of time. typical implementations use microcode to cope with the more complex instructions and facilities of s/390. current ibm s/390 processors even contain two levels of microcode.we report on an experimental s/390 processor based on a risc processor kernel employing superscalar, out of order execution of instructions. s/390 instructions have to be translated into internal sequences of risc instructions. actually two closely coupled internal sequences - one for register based execution and one for storage based execution are generated. the translation is a straight-forward mapping in most cases with some flexibility for special instructions.the paper introduces the hardware mechanisms used for mapping s/390 instructions to internal sequences. the facilities, which provide a greater degree of flexibility are discussed. the interactions of the low-level mapping scheme with the microcode levels is examined. finally we discuss our experiences with this type of implementation of a cisc architecture on a risc processor kernel. rolf hilgendorf wolfram sauer
load-sensitive routing of long-lived ip flows internet service providers face a daunting challenge in provisioning network resources, due to the rapid growth of the internet and wide fluctuations in the underlying traffic patterns. the ability of dynamic routing to circumvent congested links and improve application performance makes it a valuable traffic engineering tool. however, deployment of load-sensitive routing is hampered by the overheads imposed by link-state update propagation, path selection, and signaling. under reasonable protocol and computational overheads, traditional approaches to load-sensitive routing of ip traffic are ineffective, and can introduce significant route flapping, since paths are selected based on out-of-date link-state information. although stability is improved by performing load- sensitive routing at the flow level, flapping still occurs, because most ip flows have a short duration relative to the desired frequency of link-state updates. to address the efficiency and stability challenges of load-sensitive routing, we introduce a new hybrid approach that performs dynamic routing of long-lived flows, while forwarding short-lived flows on static preprovisioned paths. by relating the detection of long-lived flows to the timescale of link- state update messages in the routing protocol, route stability is considerably improved. through simulation experiments using a one-week isp packet trace, we show that our hybrid approach significantly outperforms traditional static and dynamic routing schemes, by reacting to fluctuations in network load without introducing route flapping. anees shaikh jennifer rexford kang g. shin