A Two-Level Flow Control Scheme for High Speed Networks

Many new network applications demand interprocess communication (IPC) services with guaranteed bandwidth, delay, and low. Existing transport protocol mechanisms have not been designed with these service objectives. Large bandwidth-delay products of high-speed networks also render the existing flow control mechanism inefficient. This paper presents the design, evaluation, and implementation of a two-level flow control scheme that can support efficient IPC for these applications in high-speed network environments

An Application-Oriented Error Control Scheme for High Speed Networks

Many new network applications demand interprocess communication (IPC) services that are not supported by existing transport network protocol mechanisms. Large bandwidth-delay products of high-speed networks also render the existing error control mechanism inefficient. This paper presents the design, evaluation, and implementations of an application-oriented error control scheme that can support efficient IPC for these applications in high-speed network environments

Efficient Quality of Service Support in Multimedia Computer Operating Systems

This report describes our approach towards providing quality of service (QoS) guarantees for network communication within the endsystems to support multimedia applications. We first address the problem of QoS specification by identifying a set of application classes and their QoS parameters that cover the communication requirements of most applications. We then describe the QoS mapping problem, and show how requirements for resources (such as the CPU, the network interface adaptor and network connections) can be automatically derived from the application QoS parameters. We then deal with the QoS enforcement issue in which we describe techniques for scheduling protocol processing threads in order to reduce context switching overhead, as well as derive sufficiency conditions in order to provide predictable performance. We integrate all these solutions in a protocol implementation model. The key feature of the model is that protocols are part of the application process and are processed using protocol threads with individual scheduling attributes derived using our QoS mapping method. We propose several performance improvement techniques for application level protocol implementations that can reduce the high cost of data movement and context switching in these implementations. A significant component of this work will consist of implementation and experimentation which will result in significant contributions of practical utility

Distributed Data Layout, Scheduling and Playout Control in a Large Scale Multimedia Storage Server

this paper, we will consider only a retrieval environment and primarily focus on the strong interaction between the architecture, data layout, data compression, and scheduling. In particular, we will present distributed multilevel data layout, scheduling and playout control schemes developed in conjunction with our architecture. These schemes allow all clients to access the same data without data replication and support both buffered as well as bufferless clients. Also, they provide strict Large Scale Multimedia Servers 2 deterministic guarantees to each active client during normal playout as well as a full spectrum of interactive stream control operations (namely, fast forward, rewind, frame advance, slow play, slow rewind, pause, stop-and-return and stop). Our implementation of the stream control operations requires no extra bandwidth reservation and provides acceptable operation latency of a few hundread milliseconds. The rest of this paper is organized as follows: Various service models that are possible for a ondemand multimedia server are illustrated in Section 2. The basics of our prototype implementation of a large scale server are presented in Section 3. Section 4 describes the distributed and hierarchical data layout scheme. Next, our basic multilevel scheduling scheme is illustrated in Section 5. Various ways of implementing playout control operations and their implications on scheduling are described in Section 6. This section also presents modifications that must be made in the basic scheduling scheme to achieve smooth transition between normal playout and operations such as ff and rw

A Simplified Reservation and State Setup Protocol

The last few years have seen the development of a model for Integrated Services Internet, which extends the traditional Internet by adding multiple service classes in addition to the traditional best effort service class, and a signaling protocol called RSVP for applications to reserve resources. While this framework has been standardized in the IETF WGs and the RSVP protocol has been defined, there has been no movement towards a commercial implementation of this framework, principally due to its perceived complexity and lack of scalability. This paper analyzes RSVP, discusses some of the its bottlenecks and shows how they can be eliminated to create a trimmer signaling protocol with enhanced functionality and scalability. We have created such a trimmed down version called SSP (State Setup Protocol). Some of the key improvements that we focus on are - single pass operation, elimination of receiver heterogeneity, single unified style of reservation, generalized filter specification, integrated label switching and third party signaling setup

Router Plugins: A Modular and Extensible Software Framework for Modern High Performance Integrated Services Routers

Present day routers typically employ monolithic operating systems which are not easily upgraded and extensible. WIth the rapid rate of protocol development it is becoming increasingly important to dynamically upgrade router software in an incremental fashion. We have designed and implemented a high performance, modular, extended integrated services router software architecture in the NetBSD operating system kernel. This architecture allows code modules, called plugins, to be dynamically added and configured at run time. One of the novel features of our design is the ability to bind different plugins to individual flows; this allows for distinct plugin implementations to seamlessly coexist in the same runtime environment. High performance is achieved through a carefully designed modular architecture; an innovative packet classification algorithm that is both pwerful and highly efficient; and by caching that exploits the flow-like characteristics of Internet traffic. Compared to a monolithic best-effort kernel, our implementation requires an average increase in packet processing overhead of only 8%, or 500 cycles/2.1microsecond per packet when running on a P6/233

Cell Tracking using a Distributed Algorithm for 3D Image Segmentation

We have developed and tested an automated method for simultaneous 3D tracking of numerous, flourescently-tagged cells. The procedure uses multiple thresholding to segment individual cells at a starting timepoint, and then iteratively applies a template-matching algorithm to locate a particular cell\u27s position at subsequent time points. To speed up the method, we have developed a distributed implementation in which template matching is carried out in parallel on several different server machines. The distributed implementation showed a monotonic decrease in response time with increasing number of servers (up to 15 tested), demonstrating that the tracking algorithm is well suited to parallelization, and that nearly real-time performance could be expected on a parallel processor. Of four different template matching statistics tested for 3D tracking of amebae from the cellular slime mold Dictyostelium discoideum, we found that the automated procedure performed best when using a correlation statistic for matching. Using this statistic, the method achieved a .985% success rate in correctly identifying a cell from one timepoint to the next. This method is now being used regularly for 3D tracking of normal and mutant cells of D. discoideum, and as such provides a means to quantify the motion of many cells within a three-dimensional tissue mass

A First Look at OpenFlow Control Plane Behavior from a Test Deployment

OpenFlow is widely being deployed across campuses in the US, Europe, and Asia. However, little is known about the performance and traffic characteristics of such networks in practice. In this paper, we present preliminary behavior and performance observations made from traffic collected at the Stanford experimental OpenFlow network, the first deployment of its kind operating with user-generated traffic. We base our study on OpenFlow control plane traffic and data plane measurements, collected over multiple weeks. We find that control plane traffic, while typically low, can, at times, make up a significant portion of overall network traffic. We observe that the flow arrival rate has a large impact on network performance. Finally, we identify several tradeoffs and practical limitations in network measurement and monitoring approaches enabled by OpenFlow

An Architecture for Monitoring, Visualization and Control of Gigabit Networks

In this paper, we outline a design of a highly scalable network monitoring, visualization and control system (NMVC) system with advanced algorithmic and human-in-the-loop capability. This capability allows network administrators to calibrate and fine-tune network and application parameters in real-time according to observed traffic patterns. The goal of the NMVC system is to ensure adequate quality of service to network users, while maintaining high network resource utilization. The main components of our system are: a network probe and an endsystem probe which can probe gigabit/s links, software network management agents that provide extensible multi-attribute event filtering for highly scalable data/event collection, efficient online event ordering algorithms that can help synthesize and display a consistent view of network health, status and performance and a View Choreographer that allows management applications and administrators to specify the mapping of network events to higher-..