FCA-ItswTCM:区分服务中一种公平的拥塞自适应标记算法

 本文提出了一种新的滑动窗口标记算法——公平的拥塞自适应标记算法(FCA-ItswTCM).算法近似识别TCP流和UDP流,适度区分标记,规避拥塞控制机制对公平性的影响;细粒度描述拥塞,预测拥塞,以此自适应调节各流注入黄包比例,兼顾网络拥塞状态对公平性的影响.仿真实验表明,与其他几种滑动窗口标记算法相比,FCA-ItswTCM对确保TCP流和UDP流带宽共享的公平性、提高资源利用率及系统稳定性有较好的效果.     

区分服务中一种拥塞感知的单速三色标记算法

确保服务的实现依赖于在边界路由器执行的数据包标记策略和在核心路由器执行的队列管理策略.TCP流由于其拥塞自适应的特点对丢包很敏感,网络拥塞对其吞吐量影响很大.为此,我们设计了一种拥塞感知的单速三色标记算法CASR3CM.仿真实验表明,该算法不仅提高了AS TCP流的平均吞吐量,而且增强了吞吐量的稳定性.另外该算法也提高了AS TCP流之间占用带宽的公平性.     

区分服务中AF类的一种调度算法

该文根据区分服务中确保转发(Assured Forwarding,AF)类的特点,设计了一种新的调度算法公平加权轮循(Fair、Weighted Round Robin,FWRR)算法。 FWRR是一种基于轮循、工作保持型、适于变长分组的调度算法.它的实现简单,算法复杂度为O(1).仿真实验和数学分析表明,FWRR算法不仅能够提供保证最小带宽的服务,而且能够按比例分配剩余带宽,适合用来调度区分服务中的AF类.     

一种改进的双速率三色标记器

提出了一种改进的双速率三色标记算法。该算法用两个上三角矩阵表示标记器之间的令牌借用关系，在某一个标记器对应的流(或者聚合流)空闲时，把它多余的令牌能够按照一定的概率借用给需要令牌的数据流。在某个数据流繁忙时，若发现自己目前的令牌不足，就向原来借用自己令牌的数据流索还一定的令牌。该算法能用来在区分服务环境下对确保传输的分组进行丢弃优先级标记。仿真结果表明，相对于原来的双速率三色标记算法，该算法能够提供较高的吞吐量。     

基于MPLS的区分服务技术实现VPN

传统的Internet只提供尽力传送服务,但这种没有任何保证,不可预测的服务已经不能满足许多应用的需要,如何在公网上架构支持QoS的VPN具有重要的现实意义。本文简单介绍了区分服务和MPLS的基本技术框架,重在探讨如何实现DiffServ/MPLS的虚拟私有网络。     

一种基于区分服务的VoIP访问控制体系

本文基于区分服务网络体系对访问控制方法进行了研究,提出了一种改进的访问控制体系。该体系以探测流和正常数据包附加测试标记的方式获取网络状况信息。据此适应性调整边界路由器的标记、资源分配等参数,使得语音数据在网络拥塞等状况下也能够获得有效服务,进一步提高网络的资源利用率。     

区分服务的改进主动队列管理算法

在区分服务模型中，具有不同微流数量、分组长度和目标速率的流聚集在资源共享时往往无法获得公平带宽。本文在自适应RIO算法基础上提出了一种区分RIO算法（Differentiated RIO，DRIO），DRIO对具有不同目标速率的流区别对待，使得无论在何种情况下都可以很好地保证各流聚集在共享带宽资源上的公平性，而且算法实现简单。仿真结果表明，DRIO对提高流聚集之间的公平性有很明显的效果。     

一种实用的域内标记算法及其公平性

本文结合宽带综合接入系统(IAS)内部标签信令格式,提出了一种自治域内部标记(Inner System Labeling)算法,分析了算法对综合业务中各流的公平性。实验结果表明,当发送端按指数比率快速向目的端瞬时速率收敛时,综合业务的所有传输流的发送速率都收敛于一个稳定值,即各流的有效流量是公平的。     

一种基于大小流区分计数的公平抽样算法

针对一种草图指导公平抽样(SGS)算法对小流估计误差大的问题,该文提出一种基于大小流区分计数的包公平抽样算法(DCMFS),并给出哈希冲突对SGS算法估计误差影响的定量分析结果。DCMFS采用大小流区分计数器,对小流采用逐流精确计数,对大流采用哈希计数。理论分析及实际的数据仿真结果均表明,DCMFS算法对小流能够实现逐流精确统计,对大流的估计标准差接近公平抽样估计标准差理论值上限。算法采用不等长位宽计数器结构,保证其空间复杂度较SGS和自适应非线性抽样方法(ANLS)没有增加;引入计数器置换使得算法时间复杂度略有提高,但仍能满足10 Gbps线速处理要求。     

一种公平的多优先级WDM光网络波长分配算法

文章研究了波分复用(WDM)光网络中动态业务下的波长分配问题,在无波长转换器的条件下,提出了一种加入了公平性考虑的动态门限算法.该算法在支持多优先级的动态门限法的基础上,通过更新初始优先级减少了不同距离光路连接请求间的阻塞率差别,改善了公平性.计算机仿真结果说明了该算法的有效性.     

利用双线性聚集签名实现公平的签名交换方案

公平的签名交换方案是实现数字合同签署、电子支付等电子商务活动的一项重要技术,它的有效实现一直是人们追求的目标。利用最近Boneh提出的基于双线性聚集签名的签名可验证加密方案,设计了一种公平的签名交换方案。该方案基于双线性群对上计算co-Diffie-Hellman假设,借助双线性映射实现加密可验证性,具有签名长度短、计算简便等优点,可有效提高公平签名交换的实现效率。     

A scalable QoS routing model for diffserv over MPLS networks

In this paper, we present a new Quality of Service (QoS) routing model for Differentiated Services (Diffserv) over Multiprotocol Label Switching (MPLS) networks. We use a pre-established multi-path model in which several MPLS label switching paths (LSPs) are established between each ingress-egress router pair in advance. Ingress routers perform per-request admission control and bulk-type resource reservation based on the resource availability on the associated LSPs. We use a utilization-based dynamic load balancing scheme to increase resource utilization across LSPs. The proposed model increases signaling and state scalability in the network core. It also provides hard QoS guarantees and minimizes admission control time. The experimental results verify the achievements of our model under various network topologies and traffic conditions.     

Throughput-based fair bandwidth allocation in OBS networks

Fair bandwidth allocation (FBA) has been studied in optical burst switching (OBS) networks, with the main idea being to map the max-min fairness in traditional IP networks to the fair-loss probability in OBS networks. This approach has proven to be fair in terms of the bandwidth allocation for differential connections, but the use of the ErlangB formula to calculate the theoretical loss probability has made this approach applicable only to Poisson flows. Furthermore, it is necessary to have a reasonable fairness measure to evaluate FBA models. This article proposes an approach involving throughput-based-FBA, called TFBA, and recommends a new fairness measure that is based on the ratio of the actual throughput to the allocated bandwidth. An analytical model for the performance of the output link with TFBA is also proposed.     

A delay‐based transport layer mechanism for fair TCP throughput over 802.11 multihop wireless mesh networks

Cities worldwide have planned and implemented large‐scale wireless mesh network (WMN) deployments. These mesh deployments are expected to provide broadband mobile access to the Internet at a low cost to the user. This paper considers the fairness problem affecting nodes in multihop WMNs. Many existing approaches to coping with the fairness problem are unsuitable because they necessitate modifications to the IEEE 802.11 MAC protocol or node queueing operations. Such modifications require a change in hardware/firmware at every node in the WMN. Thus, these approaches are less favorable from the points of view of interoperability and cost. Without modifying the lower layer protocols, this study identifies TCP parameters that impact throughput fairness and proposes an adjustment to these parameters to reduce frame collisions and to improve throughput fairness. Using simple mathematical formulations and ns2 simulations, this study shows that the frame transmissions from each node can be effectively controlled by properly controlling the delayed ACK timer and by using a suitable advertised window. The proposed method, in addition to fairness, requires fewer buffer resources than other methods. Moreover, it is not sensitive to the carrier sense range. It is also simple and easy to deploy. Copyright © 2011 John Wiley & Sons, Ltd.     

Performance analysis in multi-hop radio networks with balanced fair resource sharing

Balanced fairness is a new resource sharing concept recently introduced by Bonald and Proutière. We extend the use of this notion to wireless multi-hop networks, e.g. ad hoc networks, where the link capacities at the flow level are not fixed but depend on lower layer issues such as scheduling and interference. Utilizing this extension we present the theoretical framework for flow level performance analysis of elastic traffic in the setting, assuming that the wireless bandwidth resources are subject to linear constraints. We discuss how different physical and access layer configurations can be described by the linear constraint model and devise an efficient computational scheme for solving the system. The concepts and the computational scheme are illustrated by a number of examples.     

A short-term fair MAC protocol for WLANs

Designing a medium access control (MAC) protocol that simultaneously provides high throughput and allows individual users to share limited spectrum resources fairly, especially in the short-term time horizon, is a challenging problem for wireless LANs. In this paper, we propose an efficient cooperative MAC protocol with very simple state information that considers only collisions, like the standard IEEE 802.11 MAC protocol. However, contrary to the IEEE 802.11 MAC, the cooperative MAC gives collided users priority to access the channel by assigning them shorter backoff counters and interframe-spaces than users who did not participate in the collision event. In other words, collided users are the only ones allowed to transmit in the following contention period. For the cooperative MAC protocol, we utilize an analytical throughput model to obtain the optimal parameter settings. Simulation results show that the cooperative MAC provides significant improvement in short-term fairness and access delay, while still providing high network throughput.     

一个公平的反拒认协议

反拒认是实现电子商务的一个重要前提条件,公平也是人们在交易过程中所追求的重要目标。本文基于此目标提出了一个公平的反拒认协议, 解决了收发双方可能发生的拒认问题,并使收发双方处于平等的位置上。本协议由可靠的第三方产生反拒认证据,数据交互次数少,高效实用。     

视频流传输的网络质量保障

首先从视频流传输角度对当前研究的各种网络质量保障机制进行了介绍和分析,然后对当前研究的最新动身进行了阐述,最后介绍了基于区分服务体系结构的MPEG视频传输的研究和实验成果。     

A framework for delivering fine granularity and fair service discrimination in DiffServ networks

In order to achieve a quality of service (QoS) capable of satisfying an ever increasing range of user requirements, differentiated services (DiffServ) have been introduced as a scalable solution that emerges ‘naturally’ from today's best effort service approach. Mapping the packet treatment into a small number of per hop behaviours (PHBs) is the key idea behind the scalability of DiffServ but this comes at the cost of loosing some behavioural differentiation and some fairness between flows multiplexed into the same aggregated traffic. The paper proposes a novel simple and effective DiffServ approach, the ‘Simple Weighted Integration of diFferentiated Traffic’ (SWIFT), and uses it in a series of simulations covering a relatively wide range of local network conditions. Measured voice and video traffic traces and computer generated self‐similar background traffic were used in simulations performed at various congestion levels and for in‐profile and out‐of‐profile source behaviour. The resulted throughput, mean delay, maximum delay and jitter are used to asses SWIFT's capabilities—isolation of the in‐profile traffic from congestion effects, treatment differentiation, increased resource utilization, fairness in treatment under congestion, and incentivity for nice behaviour. Comparisons with other approaches employing traffic control are also provided. Copyright © 2003 John Wiley & Sons, Ltd.