Alpha -Channel: A Network Framework to Support Application Real-Time Performance Guarantees (original) (raw)
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1992
This paper considers the support of real-time applications in an Integrated Services Packet Network (ISPN). We rst review the characteristics of real-time applications. We observe that, contrary to the popular view that real-time applications necessarily require a xed delay bound, some realtime applications are more exible and can adapt to current network conditions. We then propose an ISPN architecture that supports two distinct kinds of real-time service: guaranteed service, which is the traditional form of realtime service discussed in most of the literature and involves pre-computed worst-case delay bounds, and predicted service which uses the measured performance of the network in computing delay bounds. We then propose a packet scheduling mechanism that can support both of these real-time services as well as accommodate datagram trac. We also discuss two other aspects of an overall ISPN architecture: the service interface and the admission control criteria.
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Proceedings of The IEEE, 1994
The dramatically increased bandwidths and processing capabilities of future high-speed networks make possible many distributed real-time applications, such as sensor-based applications and multimedia services. Since these applications will have traffic characteristics and performance requirements that differ dramatically from those of current data-oriented applications, new communication network architectures, and protocols will be required. In this paper we discuss the performance requirements and traffic characteristics of various real-time applications, survey recent developments in the areas of network architecture and protocols for supporting real-time services, and develop frameworks in which these, and future, research efforts can be considered
Scalable QoS Guaranteed Communication Services for Real-Time Applications
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In this paper, we propose an approach to flow-unaware admission control, which is combination with an aggregate packet forwarding scheme, improves scalability of networks while guaranteeing end-to-end deadlines for realtime applications. We achieve this by using an off-line delay computation and verification step, which allows to reduce the overhead at admission control while keeping admission probability and resources utilization high. Our evaluation data show our system's admission probabilities are very close to those of significantly more expensive flow-aware approaches. At the same time, admission control overhead during flow establishment is very low. Our results therefore support the claim from the DS architecture literature that scalability can be achieved through flow aggregation without sacrificing resource utilization and with significant reduction in run time overhead. ¡ . Each edge router is supposed to aggregate the individual flows into a small number of such aggregate flows. In this fashion, the DS model makes the ¢ In the following, we will use the term flow to indicate a stream of data between a source and a destination, and the term connection to indicate the virtual circuit that needs to be established to carry the flow.
The Tenet real-time protocol suite: design, implementation, and experiences
IEEE/ACM Transactions on Networking, 1996
Many future applications will require guarantees on network performance, such as bounds on throughput, delay, delay jitter, and reliability. To address this need, we have designed, simulated, and implemented a suite of network protocols to support real-time channels (network connections with mathematically provable performance guarantees). The protocols, which constitute the prototype Tenet Real-Time Protocol Suite (Suite 1), run on a packet-switching internetwork, and can coexist with the popular Internet protocol suite. We rely on the use of connection-oriented communication, per-channel admission control, channel rate control, and priority scheduling. This protocol suite is the first set of transport and network-layer communication protocols that can transfer real-time streams with guaranteed quality in packet-switching internetworks. We 1.
Real-time packet switching: a performance analysis
IEEE Journal on Selected Areas in Communications, 2000
In this paper, we model the internal structure of a packet switching node in a real-time system and characterize the tradeoff between throughput, delay, and packet loss as a function of the buffer size, switching speed, etc. We assume a simple shared single path switch fabric, though the analysis can be generalized to a wider class of switch fabrics. We show that with a small number of buffers the node will provide a guaranteed delay bound for high-priority traffic, a low-average delay for low-priority traffic, no loss of packets at the input and low probability of packet loss at output. From 1984 to 1985 he was on the faculty with the Department of Electrical Engineering at the Technion. From 1985 he is with IBM T.
V-NET: A versatile network architecture for flexible delay guarantees in real-time networks
IEEE Transactions on Computers, 2000
AbstractÐThis paper proposes a Versatile Network Architecture (-NET) to support flexible delay guarantees for applications in realtime networks. Applications communicate over the -NET by using end-to-end network connections which support real-time and reliability characteristics tailored to meet the application's specified requirements. -NET differs from other proposed architectures in that, in addition to addressing the issue of quality of service (QoS) feasibility for a wide spectrum of real-time applications, it also provides a mechanism to determine a network state dependent range of feasible delay values at each switching node along the routing path. These delay ranges can be used to assign per-node delays that reflect the resource availability of the node, thereby reducing the likelihood of bottlenecks along the routing path. The -NET delay guarantees are provided for a variety of packet scheduling algorithms and traffic policing mechanisms. This flexibility is an important design consideration as a real-time network architecture must accommodate existing and future multimedia applications, with hard-, soft-, and non-real-time traffic. The performance evaluation results demonstrate the efficiency of this scheme in handling different traffic scenarios and QoS requirements. We have shown that it is possible, and indeed efficient, to determine an upper-bound on the delay of real-time traffic, when using our per-node delay assignment policies. Fig. 2. Switching node architecture.
Computer Networks, 2006
The QoS provided by todayÕs best effort Internet is not good enough, especially for real-time interactive traffic categorized as Premium Traffic (PT). It is believed that QoS guarantees could be better provided by connection-oriented networks such as IP/MPLS. However, these connection-oriented networks are inherently more prone to network failures. Failures of connection-oriented MPLS can be broadly classified into two types namely: link/path failures and degraded failures. Degraded failures that account for about 50% of total failures are detected by the timers maintained at the control plane peers. The control plane and the data plane of IP/MPLS packet networks are logically separated and therefore a failure in the control plane should not immediately disconnect the communications in the data plane. The Virtual Path Hopping (VPH) concept in this study distinguishes these two types of failures and avoids the disconnections of communications in the data plane due to degraded failures. Thereby it reduces the number of failures in the data plane. Computer simulations were performed and the results indicate that VPH is a proactive technique that minimizes failures in the data plane. The proposed Dynamic Virtual Path Allocation (DVPA) algorithm improves the availability of the connection-oriented networks by overcoming link/path failures, especially for PT, without compromising the network resource utilization efficiency. Comprehensive simulations were performed to evaluate the DVPA algorithm and the results show the improvements that DVPA can achieve. Therefore implementation of the DVPA algorithm in conjunction with VPH would improve the reliability and availability aspects of QoS in connection-oriented IP/MPLS packet networks.
A real-time scheduling framework for packet-switched networks
14th International Conference on Distributed Computing Systems, 1994
This paper develops a unified framework for reasoning about timing correctness of packet-switched networks. The unification is in the form of a set of consistent scheduling models for a variety of network architectures and protocols. The unification is important as it allows heterogeneous network types to be analyzed using a consistent methodology and facilitates scheduling over multihop networks where each link is a different type of network. To demonstrate the framework, a scheduling model for a dual-link network, IEEE 802.5 token ring, and FDDI, is presented. The use of this framework to select paths in multi-hop networks is also demonstrated.