This paper presents Random Early Detection (RED) gate-ways for congestion avoidance in packet-switched networks. The gateway detects incipient congestion by com-puting the average queue size. The gateway could notify connections of congestion either by dropping packets ar-riving at the gateway or by setting a bit in packet headers. When the average queue size exceeds a preset threshold,the gateway drops or marks each arriving packet with a certain probability, where the exact probability is a func-tion of the average queue size. RED gateways keep the average queue size low while allowing occasional bursts of packets in the queue. During congestion, the probability that the gateway notifies a particular connection to reduce its window is roughly proportional to that connection's share of the bandwidth throughthe gateway. RED gateways are designed to accompany a transport-layer congestion control protocol such as TCP.The RED gateway has no bias against bursty traffic and avoids the global synchronization of many connectionsdecreasing their window at the same time. Simulations of a TCP/IP network are used to illustrate the performance of RED gateways.

Network arrivals are often modeled as Poisson processes for analytic simplicity, even though a number of traffic studies have shown that packet interarrivals are not exponentially distributed. We evaluate 24 wide-area traces, investigating a number of wide-area TCP arrival processes (session and connection arrivals, FTP data connection arrivals within FTP sessions, and TELNET packet arrivals) to determine the error introduced by modeling them using Poisson processes. We find that user-initiated TCP session arrivals, such as remotelogin and file-transfer, are well-modeled as Poisson processes with fixed hourly rates, but that other connection arrivals deviate considerably from Poisson; that modeling TELNET packet interarrivals as exponential grievously underestimates the burstiness of TELNET traffic, but using the empirical Tcplib [Danzig et al, 1992] interarrivals preserves burstiness over many time scales; and that FTP data connection arrivals within FTP sessions come bunched into “connection bursts,” the largest of which are so large that they completely dominate FTP data traffic. Finally, we offer some results regarding how our findings relate to the possible self-similarity of widearea traffic.

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This paper discusses the use of link-sharing mechanisms in packet networks and presents algorithms for hierarchical link-sharing. Hierarchical link-sharing allows multiple agencies, protocol families, or traflic types to share the bandwidth on a tink in a controlled fashion. Link-sharing and real-time services both require resource management mechanisms at the gateway. Rather than requiring a gateway to implement separate mechanisms for link-sharing and real-time services, the approach in this paper is to view link-sharing and real-time service requirements as simultaneous, and in some respect complementary, constraints at a gateway that can be implemented with a unified set of mechanisms. White it is not possible to completely predict the requirements that might evolve in the Internet over the next decade, we argue that controlled link-sharing is an essential component that can provide gateways with the flexibility to

This memo describes version 1 of RSVP, a resource reservation setup protocol designed for an integrated services Internet. RSVP provides receiver-initiated setup of resource reservations for multicast or unicast data flows, with good scaling and robustness properties. Internet Draft RSVP Specification November 1996 Contents 1 Introduction 3 1.1 Data Flows : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 1.2 Reservation Model : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 6 1.3 Reservation Styles : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 9 1.4 Examples of Styles : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 11 2 RSVP Protocol Mechanisms 15 2.1 RSVP Messages : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 15 2.2 Merging Flowspecs : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 16 2.3 Soft State : : : : : : : ...

Pushback is a mechanism for defending against distributed denial-of-service (DDoS) attacks. DDoS attacks are treated as a congestion-control problem, but because most such congestion is caused by malicious hosts not obeying traditional end-to-end congestion control, the problem must be handled by the routers. Functionality is added to each router to detect and preferentially drop packets that probably belong to an attack. Upstream routers are also notified to drop such packets (hence the term Pushback) in order that the router's resources be used to route legitimate traffic. In this paper we present an architecture for Pushback, its implementation under FreeBSD, and suggestions for how such a system can be implemented in core routers.

This paper introduces and analyzes a class of nonlinear congestion control algorithms called binomial algorithms, motivated in part by the needs of streaming audio and video applications for which a drastic reduction in transmission rate upon each congestion indication (or loss) is problematic. Binomial algorithms generalize TCP-style additive-increase by increasing inversely proportional to a power of the current window (for TCP, ) ; they generalize TCP-style multiplicative-decrease by decreasing proportional to a power of the current window (for TCP, ). We show that there are an infinite number of deployable TCP-compatible binomial algorithms, those which satisfy , and that all binomial algorithms converge to fairness under a synchronized-feedback assumption provided . Our simulation results show that binomial algorithms interact well with TCP across a RED gateway. We focus on two particular algorithms, IIAD ( ) and SQRT ( !" ), showing that they are well-suited to applications that do not react well to large TCP-style window reductions. Keywords--- Congestion control, TCP-friendliness, TCP-compatibility, nonlinear algorithms, transport protocols, TCP, streaming media, Internet. I.

This paper considers the potential negative impacts from an increasing deployment of non-congestion-controlled besteffort traffic on the Internet. These negative impacts range from extreme unfairness against competing TCP traffic to the potential for congestion collapse. To promote the inclusion of end-to-end congestion control for best-effort traffic, we propose lightweight router mechanisms for identifying and restricting the bandwidth of high-bandwidth best-effort flows that are using a disproportionate share of the bandwidth in times of congestion. Our method does not require per-flow state based on packet arrivals, but instead relies on the history of packet drops from a queue with RED (Random Early Detection) queue management. Starting with high-bandwidth flows identified from the RED drop history, we describe a sequence of tests capable of suggesting flows for bandwidth regulation. These tests additionally identify a high-bandwidth flow in times of congestion as unresponsive, "n...

Workflow management systems (WfMSs) have been used to support various types of business processes for more than a decade now. In workflows for e-commerce and Web-services applications, suppliers and customers define a binding agreement or contract between the two parties, specifying Quality of Service (QoS) items such as products or services to be delivered, deadlines, quality of products, and cost of services. The management of QoS metrics directly impacts the success of organizations participating in e-commerce. Therefore, when services or products are created or managed using workflows, the underlying workflow system must accept the specifications and be able to estimate, monitor, and control the QoS rendered to customers. In this paper, we present a predictive QoS model that makes it possible to compute the quality of service for workflows automatically based on atomic task QoS attributes. To this end, we present a model that specifies QoS and describe an algorithm and a simulation system in order to compute, analyze and monitor workflow QoS metrics. 1

ABSTRACT The integration of distributed multimedia systems support into a communications architecture encompassing the new multiservice networks poses significatu challenges. A key observation about the new environment is that Quality of Service (QOS) provides a unifying theme around which most of the new communications requirements can be grouped. For applications relying on the transfer of multimedia information, and in particular continuous media, it is essential that QOS is guaranteed system-wide, including the distributed system pqorm, the tramport protocol and the multiservice network. Enhanced protocol support such as end-to-end QOS negotiation, renegotiation, indication of QOS degradations and co-ordination over multiple related connectwm are also required. Little attention, however, has so far been paid to the defw'tion of a coherent framework that incorporates QOS interfaces, management and mechanisms across all the layers. This paper describes the first stage in the development of an integrated Quality of Service Architecture (QOS-A) which offers a framework to specifr and implement the required performance properties of new multimedia applications over multiservice ATM-based networks. 1.