Abstract not found

Active networks allow their users to inject customized programs into the nodes of the network. An extreme case, in which we are most interested, replaces packets with "capsules" -- program fragments that are executed at each network router/switch they traverse. Active architectures permit a massive increase in the sophistication of the computation that is performed within the network. They will enable new applications, especially those based on application-specific multicast, information fusion, and other services that leverage network-based computation and storage. Furthermore, they will accelerate the pace of innovation by decoupling network services from the underlying hardware and allowing new services to be loaded into the infrastructure on demand. In this paper, we describe our vision of an active network architecture, outline our approach to its design, and survey the technologies that can be brought to bear on its implementation. We propose that the research community mount a j...

In this article we present a framework for the emerging Internet quality of service (QoS). All the important components of this framework --- integrated services, RSVP, differentiated services, multiprotocol label switching (MPLS), and constraintbased routing --- are covered. We describe what integrated services and differentiated services are, how they can be implemented, and the problems they have. We then describe why MPLS and constraint-based routing have been introduced into this framework, how they differ from and relate to each other, and where they fit into the differentiated services architecture. Two likely service architectures are presented, and the end-to-end service deliveries in these two architectures are illustrated. We also compare ATM networks to router networks with differentiated services and MPLS. Putting all these together, we give the readers a grasp of the big picture of the emerging Internet QoS. 12 IEEE Network . March/April 1999 9 and differenti...

One of the Internet’s greatest strengths is that it does not know or care what its applications are or what they are doing: it simply forwards data. Yet network users experience the network through the functioning and performance of applications. This divergence of perspective leads to a number of problems. For example, a user whose local DNS service has failed may perceive the network as broken, even though from a network perspective, data continues to flow correctly. If an email server or a Web server fails, the user will say the network is broken; the network operator will say the network is fine. We need a way to make the network more aware of itself and its applications, without destroying the open and transparent data plane. To meet this need we propose the creation of an Internet knowledge plane. The knowledge plane is a distributed and decentralized construct within the network that gathers, aggregates, and manages information about network behavior and operation, and provides an integrated view to all parties (operators, users, and the network itself). The goal is to enlarge our view of what constitutes the network to match the intuition of a user, and to enhance our ability to manage the network intelligently, without disturbing the open and unknowing forwarding plane. The knowledge plane is intelligent: it can reason about the network’s behavior and act upon the results of its reasoning. It can remember and learn from past behavior. To achieve that goal, we propose to adapt and employ recent work in cognition such as the separation of algorithm, policy and goals, and new models for knowledge representation.

This paper presents a novel loss recovery scheme, Active Reliable Multicast (ARM), for large-scale reliable multicast. ARM is "active" in that routers in the multicast tree play an active role in loss recovery. Additionally, ARM utilizes soft-state storage within the network to improve performance and scalability. In the upstream direction, routers suppress duplicate NACKs from multiple receivers to control the implosion problem. By suppressing duplicate NACKs, ARM also lessens the traffic that propagates back through the network. In the downstream direction, routers limit the delivery of repair packets to receivers experiencing loss, thereby reducing network bandwidth consumption. Finally, to reduce wide-area recovery latency and to distribute the retransmission load, routers cache multicast data on a "best-effort" basis. ARM is flexible and robust in that it does not require all nodes to be active, nor does it require any specific router or receiver to perform loss recovery. Analysis...

The growing use of multimedia communication applications with specific bandwidth and real-time delivery requirements has created the need for an Integrated Services Internet in which traditional best-effort datagram delivery can coexist with additional enhanced Quality Of Service(QOS) delivery classes. Such classes provide data flows with QOS commitments with regard to bandwidth, packet loss and delay through the reservation of network resources along the data path which can be done using the Resource ReSerVation Protocol (RSVP). This paper is a tutorial on how RSVP can be used by end-applications to ensure that they receive the end-to-end QOS that they require. Keywords Controlled-Load Service Data Flow Guaranteed Service Integrated Services (IS) One Pass with Advertising (OPWA) Quality of Service (QOS) ReSerVation setup Protocol (RSVP) This paper appeared in the May 1997 Issue of IEEE Communications magazine 2 1.0 Introduction The current Internet consists of a multitude of networ...

* The current World-Wide Web service model treats all requests equivalently, both while being processed by servers and while being transmitted over the network. For some uses, such as web prefetching or multiple priority schemes, different levels of service are desirable. This paper presents three simple, server-side, application -level mechanisms (limiting process pool size, lowering process priorities, limiting transmission rate) to provide two different levels of web service (regular and low priority). We evaluated the performance of these mechanisms under combinations of two foreground workloads (light and heavy) and two levels of available network bandwidth (10Mb/s and 100Mb/s). Our experiments show that even with background traffic sufficient to saturate the network, foreground performance is reduced by at most 4-17%. Thus, our user-level mechanisms can effectively provide different service classes even in the absence of operating system and network support. 1. Introduction The ...

The Differentiated services (diffserv) architecture has been proposed as a scalable solution for providing service differentiation among flows without any per-flow buffer management inside the core of the network. It has been advocated that it is feasible to provide service differentiation among a set of flows by choosing an appropriate "markingprofile"for each flow. In this paper, we examine (i) whether it is possible to provide service differentiation among a set of TCP flows by choosing appropriate marking profiles for each flow, (ii) under what circumstances, the marking profiles are able to influencethe service that a TCP flow receives, and, (iii) how to choose a correct profileto achieve a given service level. We derive a simple, and yet accurate, analytical model for determining the achieved rate of a TCP flow when edge-routers use "token bucket"packet marking and core-routers use active queue management for preferential packet dropping. From our study, we observe three important results: (i) the achieved rate is not proportional to the assured rate, (ii) it is not always possible to achieve the assured rate and, (iii) there exist ranges of values of the achieved rate for which token bucket parameters have no influence. We findthat it is not easy to regulate the service level achieved by a TCP flow by solely setting the profileparameters. In addition, we derive conditions that determine when the bucket size influencesthe achieved rate, and rates that can be achieved and those that cannot. Our study provides insight for choosing appropriate token bucket parameters for the achievable rates.

Abstract. There is a large, popular, and growing literature on “scale-free ” networks with the Internet along with metabolic networks representing perhaps the canonical examples. While this has in many ways reinvigorated graph theory, there is unfortunately no consistent, precise definition of scale-free graphs and few rigorous proofs of many of their claimed properties. In fact, it is easily shown that the existing theory has many inherent contradictions and that the most celebrated claims regarding the Internet and biology are verifiably false. In this paper, we introduce a structural metric that allows us to differentiate between all simple, connected graphs having an identical degree sequence, which is of particular interest when that sequence satisfies a power law relationship. We demonstrate that the proposed structural metric yields considerable insight into the claimed properties of SF graphs and provides one possible measure of the extent to which a graph is scale-free. This structural view can be related to previously studied graph properties such as the various notions of self-similarity, likelihood, betweenness and assortativity. Our approach clarifies much of the confusion surrounding the sensational qualitative claims in the current literature, and offers a rigorous and quantitative alternative, while suggesting the potential for a rich and interesting theory. This paper is aimed at readers familiar with the basics of Internet technology and comfortable with a theorem-proof style of exposition, but who may be unfamiliar with the existing literature on scale-free networks. 1.

In this paper, we present a novel fair queueing scheme, which we call Smoothed Round Robin (SRR). Ordinary round robin schedulers are well known for their burstiness in the scheduling output. In order to overcome this problem, SRR codes the weights of the flows into binary vectors to form a Weight Matrix, then uses a Weight Spread Sequence (WSS), which is specially designed to distribute the output more evenly, to schedule packets by scanning the Weight Matrix. By using the WSS and the Weight Matrix, SRR can emulate the Generalized Processor Sharing (GPS) well. It possesses better short-term fairness and schedule delay properties in comparison with various round robin schedulers. At the same time, it preserves O(1) time complexity by avoiding the time-stamp maintenance employed in various Fair Queueing schedulers. Simulation and implementation experiments show that SRR can provide good average end-to-end delay for soft real-time services. SRR can also be implemented in highspeed networks to provide QoS for its simplicity and low time complexity.