A new concept of fairness in flow‐aware networking

We demonstrate a new approach to assuring fairness in flow‐aware networking. Standard routine in flow‐aware networking guarantees that each flow receives the same amount of resources. This property can be exploited by dividing a single transmission into a number of flows. We propose and evaluate the per‐user fair packet scheduling mechanism, which ensures fairness among users (not flows). We also compare the new mechanism with the one already known from the literature, which is based on altering the admission control routine. Evaluation shows that the new concept of fairness provides better performance and fair resource distribution regardless of the behavior of users.     

A Macro Model of Frequently Changing Mobile Networks to Perform Flow and Access Control

The area covered by a mobile ad hoc network consists of obstacles that inhibit transmission and areas where communications can take place. Physical structures, such as buildings, that block transmission, or lakes, where forwarding nodes cannot be located, are permanent obstacles. Temporary obstacles are created as mobile nodes enter or leave an area. Our hypothesis is that the spaces between nearby obstacles are bottlenecks that inhibit the flows in the network. We partition the network into areas that are encompassed by obstacles and bottlenecks. All of the nodes in an area are treated as a single super node, and the bottlenecks between areas are the links between the super nodes. As individual nodes move, the flows and paths in the model change more slowly than the paths and flows between the individual nodes. We apply flow control algorithms to the model and perform admission control within a super node based on the flows that are assigned by the flow control algorithm. We apply the model to the Columbia University campus, and use max–min, fair bottleneck flow control to assign the flows. Our hypothesis is verified for this example.     

数据流的活动队列管理算法:MBLUE

MBLUE(Modified BLUE)是一种面向数据流的活动队列管理算法.它不是使用平均队列长度指示缓冲区拥塞状态,而是使用数据报丢弃的频率和队列空闲程度来管理网络拥塞.探测瓶颈连接早期的拥塞信息,通过数据报的丢弃和标记避免拥塞.它只维护一个先进先出队列,以较少的数据流状态信息,在不同流之间公平的分配网络带宽.能够适应瞬时的猝发流,能合理控制非TCP数据流,又能够保持较短的平均队列长度,从而控制、减轻网络拥塞.通过TCP/IP网络的模拟,证实算法在公平的分配网络带宽和降低数据报的丢失率上具有较好的鲁棒性.     

On network bandwidth sharing for transporting rate‐adaptive packet video using feedback

While existing research shows that feedback‐based congestion control mechanisms are capable of providing better video quality and higher link utilization for rate‐adaptive packet video, there has been relatively little study on how to share network bandwidth among competing rate‐adaptive video connections, when feedback control is used in a fully distributed network. This paper addresses this issue by presenting a framework of network bandwidth sharing for transporting rate‐adaptive packet video using feedback. We show how a weight‐based bandwidth sharing policy can be used to allocate network bandwidth among competing video connections and design a feedback control algorithm using an Available Bit Rate (ABR)‐like flow control mechanism. A novel video source rate adaptation algorithm is also introduced to decouple a video source's actual transmission rate from the rate used for distributed protocol convergence. Our feedback control algorithm provides guaranteed convergence and smooth source rate adaptation to our weight‐based bandwidth sharing policy under any network configuration and any set of link distances. Finally, we show the on‐line minimum rate renegotiation and weight adjustment options in our feedback control algorithm, which offer further flexibility in network bandwidth sharing for video connections. Copyright © 2000 John Wiley & Sons, Ltd.     

A guaranteed minimum throughput service for TCP flows using measurement‐based admission control

We propose a new scheme for a network service that guarantees a minimum throughput to flows accepted by admission control (AC). The whole scheme only uses a small set of packet classes in a core‐stateless network. At the ingress of the network each flow packet is marked into one of the sets of classes, and within the network, each class is assigned a different discarding priority. The AC method is based on edge‐to‐edge per‐flow throughput measurements using the first packets of the flow, and it requires flows to send with a minimum rate. We evaluate the scheme through simulations in a simple bottleneck topology with different traffic loads consisting of TCP flows that carry files of varying sizes. We use a modified TCP source with a new algorithm that forces the source to send with a minimum rate. We compare our scheme with the best‐effort service and we study the influence of the measurement duration on the scheme's performance. The results prove that the scheme guarantees the requested throughput to accepted flows and achieves a high utilization of network resources. Copyright © 2006 John Wiley & Sons, Ltd.     

TCP-friendly flow control of wireless multimedia using ECN marking

In a wireless network packet losses can be caused not only by network congestion but also by unreliable error-prone wireless links. Therefore, flow control schemes which use packet loss as a congestion measure cannot be directly applicable to a wireless network because there is no way to distinguish congestion losses from wireless losses. In this paper, we extend the so-called TCP-friendly flow control scheme, which was originally developed for the flow control of multimedia flows in a wired IP network environment, to a wireless environment. The main idea behind our scheme is that by using explicit congestion notification (ECN) marking in conjunction with random early detection (RED) queue management scheme intelligently, it is possible that not only the degree of network congestion is notified to multimedia sources explicitly in the form of ECN-marked packet probability but also wireless losses are hidden from multimedia sources. We calculate TCP-friendly rate based on ECN-marked packet probability instead of packet loss probability, thereby effectively eliminating the effect of wireless losses in flow control and thus preventing throughput degradation of multimedia flows travelling through wireless links. In addition, we refine the well-known TCP throughput model which establishes TCP-friendliness of multimedia flows in a way that the refined model provides more accurate throughput estimate of a TCP flow particularly when the number of TCP flows sharing a bottleneck link increases. Through extensive simulations, we show that the proposed scheme indeed improves the quality of the delivered video significantly while maintaining TCP-friendliness in a wireless environment for the case of wireless MPEG-4 video.     

Entropy Based Adaptive Flow Aggregation

Internet traffic flow measurement is vitally important for network management, accounting and performance studies. Cisco's NetFlow is a widely deployed flow measurement solution that uses a configurable static sampling rate to control processor and memory usage on the router and the amount of reporting flow records generated. But during flooding attacks the memory and network bandwidth consumed by flow records can increase beyond what is available. Currently available countermeasures have their own problems: 1) reject new flows when the cache is full - some legitimate new flows will not be counted; 2) export not-terminated flows to make room for new ones - this will exhaust the export bandwidth; and 3) adapt the sampling rate to traffic rate - this will reduce the overall accuracy of accounting, including legitimate flows. In this paper, we propose an entropy based adaptive flow aggregation algorithm. Relying on information-theoretic techniques, the algorithm efficiently identifies the clusters of attack flows in real time and aggregates those large number of short attack flows into a few metaflows. Compared to currently available solutions, our solution not only alleviates the problem in memory and export bandwidth, but also significantly improves the accuracy of legitimate flows. Finally, we evaluate our system using both synthetic trace file and real trace files from the Internet.     

Efficient congestion control mechanism for flow‐aware networks

Transmission based on flows becomes more and more popular in teleinformatics networks. To guarantee proper quality of service, to enable multipath transmissions, or just to increase transmission effectiveness in a network, traffic should be sent as flows. Flow‐aware networking architecture is one of the possible concepts to realize flow‐based transmissions. In this paper, the efficient congestion control mechanism (ECCM) is proposed to improve transmission in flow‐aware networks (FAN). The mechanism makes it possible to minimize acceptance delay of streaming flows (served with high priority) without deteriorating other transmissions in the network. It is confirmed by simulation experiments that the implementation of FAN with the ECCM mechanism is a promising solution for the Future Internet. Copyright © 2015 John Wiley & Sons, Ltd.     

Size-based scheduling to improve the performance of short TCP flows

The Internet today carries different types of traffic that have different service requirements. A large fraction of the traffic is either Web traffic requiring low response time or peer-to-peer traffic requiring high throughput. Meeting both performance requirements in a network where routers use droptail or RED for buffer management and FIFO as the service policy is an elusive goal. It is therefore worthwhile to investigate alternative scheduling and buffer management policies for bottleneck links. We propose to use the least attained service (LAS) policy to improve the response time of Web traffic. Under LAS, the next packet to be served is the one belonging to the flow that has received the least amount of service. When the buffer is full, the packet dropped belongs to the flow that has received the most service. We show that under LAS, as compared to FIFO with droptail, the transmission time and loss rate for short TCP flows are significantly reduced, with only a negligible increase in transmission time for the largest flows. The improvement seen by short TCP flows under LAS is mainly due to the way LAS interacts with the TCP protocol in the slow start phase, which results in shorter round-trip times and zero loss rates for short flows.     

Reconfigurable Architecture for Network Flow Analysis

This paper describes a reconfigurable architecture based on field-programmable gate-array (FPGA) technology for monitoring and analyzing network traffic at increasingly high network data rates. Our approach maps the performance-critical tasks of packet classification and flow monitoring into reconfigurable hardware, such that multiple flows can be processed in parallel. We explore the scalability of our system, showing that it can support flows at multi-gigabit rate; this is faster than most software-based solutions where acceptable data rates are typically no more than 100 million bits per second.     

一种基于RTCP协议的流量控制算法

介绍了RTP（实时传输协议）流量控制的步骤和可用的流量控制措施,分析了传统流量控制算法的不足,在此基础上,提出了一种改进流量控制算法。该算法通过改变RR（接收者报告）报文的发送规则,设置两个丢包率门限,以及同时调整报文发送周期和数据编码方式等途径,以减小丢包率,提高数据流的平稳性。仿真结果表明,改进流量控制算法能够根据丢包率对RTP数据报文的发送周期和数据编码方式进行自动调整,并有效消除由于丢包率波动而引起的流量变化。     

Distributed Flow Admission Control for Multimedia Services Over Wireless Ad Hoc Networks

In this paper we propose a novel Priority-based Distributed flow Admission Control (PDAC) protocol to provide Quality of Service (QoS) to multimedia applications over the Dynamic Source Routing (DSR) protocol-based wireless ad hoc networks. In contrast to short-term packet forwarding, medium and long-term multimedia and real-time traffic may benefit from ‘flow’-based transmission due to the reduction in the packet-level control overhead. In this paper, we introduce a new DSR option called the “Admission Control Option” for flow establishment, and present a new scalable transmission rate reservation protocol to support bandwidth-constrained traffic flows in interference-limited wireless ad hoc networks. It allows a node in the wireless ad hoc network to establish or discard a traffic flow state based on the global knowledge of traffic flow priority, and local knowledge in the form of interference and effective transmission rate. The PDAC scheme can also operate in a ‘cross-layer’ protocol architecture that encompasses the network layer and the MAC layer.     

Interference‐aware MAC scheduling and admission control for multiple mobile WBANs used in healthcare monitoring

In this paper, we address the problem of interference when multiple time division multiple access‐based wireless body area networks (WBANs) come in the proximity of one another. We propose a simple solution that creates common non‐conflicting schedule between these interfering WBANs. Our proposed scheme allows the reuse of maximum possible time slots among WBANs that are two‐hop neighbors of one another. A flow admission control scheme is applied to control the flows during the period of interference. We show that the percentage of flows admitted because of flow control decreases with the increase in the network size and flow rate. We simulated a scenario where WBANs move randomly within a simulation area with a certain speed and meet at a particular point. We show that the signal to interference noise ratio (SINR) value of WBANs changes as long as they are within the transmission range of one another. Also, we show that the exchanges of common schedule (which is dependent on the number of times the SINR value drops below the threshold) are required in order to improve the packet delivery ratio in WBANs. Copyright © 2014 John Wiley & Sons, Ltd.     

Generalized guaranteed rate scheduling algorithms: a framework

In this paper, we define a class of generalized guaranteed rate (GR) scheduling algorithms that includes algorithms which allocate a variable rate to the packets of a flow. We define work-conserving generalized virtual clock, packet-by-packet generalized processor sharing, and self-clocked fair queueing scheduling algorithms that can allocate a variable rate to the packets of a flow. We also define scheduling algorithms suitable for servers where packet fragmentation may occur. We demonstrate that if a class of rate controllers is employed for a flow in conjunction with any scheduling algorithm in GR, then the resulting non-work-conserving algorithm also belongs to GR. This leads to the definition of several non-work-conserving algorithms. We then present a method for deriving the delay guarantee of a network of servers when: (1) different rates are allocated to packets of a flow at different servers along the path and the bottleneck server for each packet may be different, and (2) packet fragmentation and/or reassembly may occur. This delay guarantee enables a network to provide various service guarantees to flows conforming to any specification. We illustrate this by utilizing delay guarantee to derive delay bounds for flows conforming to leaky bucket, exponentially bounded burstiness, and flow specification. Our method for determining these bounds is valid in internetworks and leads to tighter results     

Cross-Layer Optimization of MAC and Network Coding in Wireless Queueing Tandem Networks

In wireless networks, throughput optimization is an essential performance objective that cannot be adequately characterized by a single criterion (such as the minimum transmitted or sum-delivered throughput) and should be specified over all source-destination pairs as a rate region. For a simple and yet fundamental model of tandem networks, a cross-layer optimization framework is formulated to derive the maximum throughput region for saturated multicast traffic. The contents of network flows are specified through network coding (or plain routing) in network layer and the throughput rates are jointly optimized in medium access control layer over fixed set of conflict-free transmission schedules (or optimized over transmission probabilities in random access). If the network model incorporates bursty sources and allows packet queues to empty, the objective is to specify the stability region as the set of maximum throughput rates that can be sustained with finite packet delay. Dynamic queue management strategies are used to expand the stability region toward the maximum throughput region. Network coding improves throughput rates over plain routing and achieves the largest gains for broadcast communication and intermediate network sizes. Throughput optimization imposes fundamental tradeoffs with transmission and processing energy costs such that the throughput-optimal operation is not necessarily energy efficient.     

一种Iub口流控策略在HSPA＋系统中的应用

为了提高系统无线资源的利用率和网络性能,提出一种基于过准入的HSPA＋系统的Iub口流量控制策略。通过Iub口拥塞检测和L2流控处理,避免拥塞和丢包,提高传输利用率。仿真结果表明,该流量控制策略能有效降低拥塞,提高网络性能,并能保证业务的公平性。     

基于多核优化的网络内容监测系统优化策略

网络中的不良信息通常以电子邮件、网页浏览、论坛发布等形式进行传播,针对网络内容监测系统存在的报文数据压缩、译码传输和关键字匹配等性能问题,本文提出了一种网络内容监测系统的多核平台性能优化策略,并将其应用到系统中进行测试。实验表明：当核心处理器的计算核心数量增加到7个时,完成多核优化的网络内容监测系统的数据吞吐量能够达到优化之前的436.1%,有效提高了系统的网络性能。     

A TCP-tailored approach to location management in mobile ad hoc networks

The main location management proposals in mobile ad hoc networks have, as a common characteristic, two distinct phases: the location query of the position of a destination node and the transmission of a flow toward the destination node. This letter proposes to send the initial packet of a flow to learn the position of its destination instead of adopting a dedicated query packet. Such an approach specially benefits TCP flows. This TCP-tailored approach can be applied to previous proposals in location management with minor changes in their particular features. We show that the proposed TCP-tailored approach reduces the cost of location management for TCP flows with respect to conventional schemes. We also evaluate the benefits that different location services take from the TCP-tailored approach.     

Flow Routing and its Performance Analysis in Optical IP Networks

Optical packet-switching networks deploying buffering, wavelength conversion and multi-path routing have been extensively studied in recent years to provide high capacity transport for Internet traffic. However due to packet-based routing and switching, such a network could result in significant disorder and delay variation of packets when they are received by end users, thus increasing the burstiness of the Internet traffic and causing higher-layer protocol to malfunction. This paper addresses a novel routing and switching method for optical IP networks — flow routing, and its facilitating protocol. Flow routing deals with packet-flows to reduce flow corruption due to packet out-of-order, delay variation and packet loss, without using complicate control mechanism. Detailed performance analysis is given for output-buffered optical routers adopting flow routing. Two flow-oriented discarding techniques, i.e., flow discard (FD) and early flow discard (EFD), are discussed. Compared with optical packet-switching routers, a remarkable improvement of good-throughput is obtained in the optical flow-routers, especially under high congestion periods. We conclude that EFD behaves as a robust technique, which is more tolerant than FD to the change of traffic and transmission system factors.     

Multicast Flow Aggregation in IP over Optical Networks

It is widely believed that IP over optical networks will be a major component of the next generation Internet However, it is not efficient to map a single multicast IP flow into one light-tree, since the bandwidth of an IP flow required is usually much less than that of a light-tree. In this paper, we study the problem of multicast flow aggregation (MFA) in the IP over optical two-layered networks under the overlay model, which can be defined as follows: given a set of head ends (i.e. optical multicasting sources), each of which can provide a set of contents (i.e. multicast IP flows) with different required transmission bandwidth, and a set of requested content at the access routers (i.e. optical multicasting destinations), find a set of light-trees as well as the optimal aggregation of multicast IP flows in each light-tree. We model MFA by a tri-partite graph with multiple criteria and show that the problem is NP-complete. Optimal solutions are designed by exploiting MFA to formulate an integer linear programming (ILP), with two parameters: the multicast receiving index alpha and the redundant transmitting index beta. We also propose a heuristic algorithm. Finally, we compare the performance of MFA for different combination of alpha and beta via experiments and show our heuristic algorithm is effective for large-scale network in numerical results