81 research outputs found
, Guru Parulkar ¡
No full textAbstract — ¢ Packet filters are rules for classifying packets based on their header fields. Packet classification is essential to routers supporting services such as Quality of Service (QoS), Virtual Private Networks (VPNs), and firewalls. A filter conflict occurs when two or more filters overlap, creating an ambiguity in packet classification. Current techniques for resolving filter conflicts are based on prioritizing conflicting filters, and choosing the higher priority filter. We show that such ordering does not always work. Instead, we propose a new scheme for conflict resolution, which is based on the idea of adding resolve filters. Our main results are algorithms for detecting and resolving conflicts in a filter database. We have tried our algorithm on 3 existing firewall databases, and have found conflicts, which are potential security holes, in each of them. Keywords—Packet Filters, Classification, Security, Firewalls I
An Architecture for Monitoring, Visualization and Control of Gigabit Networks
No full textIn 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-..
Universal Continuous Media I/o: Design And Implementation
No full textThe problem this paper addresses is how to modify an existing operating system's I/O subsystem to support new high-speed networks and high-bandwidth multimedia applications that will play an important role in future computing environments. The proposed I/O subsystem is called universal continuous media I/O (UCM I/O). This paper will cover the preliminary design of UCM I/O, some of the trade-offs and issues that need to be addressed in order to implement UCM I/O, and a a summary of work in progress. This work supported by ARPA, NSF, Ascom Timeplex, BNR, Goldstar, NEC America, NTT, Southwestern Bell, SynOptics, and Tektronix. UNIVERSAL CONTINUOUS MEDIA I/O: DESIGN AND IMPLEMENTATION Charles D. Cranor [email protected] +1 314 935 4203 Gurudatta M. Parulkar [email protected] +1 314 935 4621 1. Introduction As computers become more common and powerful, new applications are being proposed. Applications in areas such as distributed computing, imaging, and multimedia are becoming..
Real-time Upcalls: A Mechanism to Provide Real-time Processing Guarantees
No full textReal-time upcalls (RTUs) are an operating systems mechanism that can be used by applications to efficiently schedule code segments (or handlers) that must execute periodically. While the mechanism was conceived to support protocol processing with quality-of-service guarantees for networked multimedia applications it is general enough to be applicable in other domains like real-time image processing. Until now real-time threads have been the only mechanism for implementing protocols in user space with QoS guarantees. The RTU mechanism avoids the implementation complexity of the thread based approach while retaining its ability to ensure real-time behavior. In addition, our design simplifies protocol code, improves performance, and can be ported to most systems. A key feature of RTU scheduling is the pre-emption scheme that exploits the iterative nature of protocol processing by allowing an RTU to yield the CPU by returning from the invocation. This obviates the need for RTU handlers to..
Catching Up With the Networks: Host I/O at Gigabit Rates
No full textThe last few years have seen network data rates skyrocket from a few Mbps to a Gbps or more. However, a lack of integration of the host-network interface, the operating system, and network protocols has resulted in end-applications seeing only a small fraction of this total bandwidth being available for data transfer. The emergence of demanding applications in the realms of multimedia and virtual reality provides further impetus in the drive to overcome this problem. In this paper, we present the design of a high performance ATM host-network interface for workstations and servers that can support a bidirectional sustained data rate in excess of a gigabit per second. A prototype of the interface is being built at Washington University as part of an ARPA-sponsored gigabit local ATM testbed. Our interface design, which emphasizes seamless integration with the OS and network protocols, features: support for streaming data from I/O devices (e.g., cameras, disk arrays, etc.) to the network or vice-versa, as well as from device-to-device, while bypassing the main system bus; an ATM interconnect that extends to the desk-area; a zero-copy interface to system memory that is achieved through the use of page remapping techniques; full AAL-5 segmentation and reas-sembly; pacing control that provides for single-parameter bandwidth reservation; a high degree of scalabil-ity in terms of the number of I/O devices that can be simultaneously supported; low-cost (one ASIC); and multiprocessor support
Error Control for Continuous Media and Multipoint Applications
No full text: High-bandwidth multimedia applications pose new challenges to error control. These include the support of error control for Continuous Media (CM) streams and the scalable support of error control in multipoint applications where the number of participants is large. Current error control mechanisms provide no support for the above applications. In this report we present new error control mechanisms that provide the required support. Continuous media applications have strict timing requirements which greatly affect recovery. To support continuous media applications we have designed and implemented a point-to-point error control mechanism which features the following: (1) selective repeat retransmission, (2) conditional retransmission, (3) playout buffering to increase the time available for recovery, (4) gap-based rather than timer-based loss detection to reduce loss detection latency, and (5) data integrity information delivery to the application. We present our design, implementation..
A Two-Level Flow Control Scheme for High Speed Networks
No full textMany 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
No full textMany 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
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