Wide-area IP multicast traffic characterization

IP multicast is gaining acceptance among service providers as the protocols and infrastructure mature. However, characteristics of multicast traffic remain poorly understood. Using passive OC-12 monitors, we observed multicast traffic on links connecting aggregated customers and peer networks to our native multicast backbone network. We first refined existing traffic flow profiling methodologies via an exploration of temporal differences in multicast packet trains. Based on this framework, we collected multicast flow traces from four geographically dispersed nodes in the Worldcom vBNS network over a one-month period. We present multicast-specific traffic characteristics including packet and flow sizes, fragmentation, sources per group, and address space distribution. Analysis reveals results contrary to prevailing wisdom, including a preponderance of single-packet flows; a highly variable packet size distribution, with many large packets and strong modes; the existence of fragmented multicast traffic; and an insignificant number of simultaneous multiple-source groups. Based on our analysis, we recommend policies for deployment and improvements to protocol implementations.     

Internet traffic engineering

The main goal of Internet traffic engineering is to efficiently optimize the performance of operational networks in order to avoid the well-known shortcomings of the typical destination-based IP routing. Traffic engineering attempts to reduce or even avoid congestion hot spots and to improve resource utilization across the backbone IP network. During the last years traffic engineering has become an inevitable tool concerning performance optimization in large Internet backbones. The core objective of this paper is to give an overview of the architectures and mechanisms for traffic engineering.     

Multi-timescale Internet traffic engineering

The Internet is a collection of packet-based hop-by-hop routed networks. Internet traffic engineering is the process of allocating resources to meet the performance requirements of users and operators for their traffic. Current mechanisms for doing so, exemplified by TCP's congestion control or the variety of packet marking disciplines, concentrate on allocating resources on a per-packet basis or at data timescales. This article motivates the need for traffic engineering in the Internet at other timescales, namely control and management timescales, and presents three mechanisms for this. It also presents a scenario to show how these mechanisms increase the flexibility of operators' service offerings and potentially also ease problems of Internet management.     

Internet traffic, QoS, and pricing

Based on an analysis of the statistical nature of IP traffic and the way this impacts the performance of voice, video, and data services, we question the appropriateness of commonly proposed quality-of-service mechanisms. This paper presents the main points of this analysis. We also discuss pricing issues and argue that many proposed schemes are overly concerned with congestion control to the detriment of the primary pricing function of return on investment. Finally, we propose an alternative flow-aware networking architecture based on a novel router design called cross-protect. In this architecture, performance requirements are satisfied without explicit service differentiation, creating a particularly simple platform for the converged network.     

Photons and petabits [for Internet traffic]

With Internet traffic doubling every few months, the author reports on one company's plans for averting gridlock in cyberspace. As the demands on the network have soared, driven by the growth of new traffic types and an increasing competitive market place, system complexity is giving way to something more akin to incipient chaos. Market pull and technology push have combined to produce a multi-layered network architecture. This comprises an access layer, IP layer, ATM layer, SDH layer, all overlaid with an optical transport layer     

基于智能手机和移动互联网的交通控制系统研究

设计一款基于智能手机和移动互联网的交通控制系统,利用移动终端与WiFi模块之间的无线通信,将控制信息传递给ARM嵌八式系统进行处理转换,进而对交通灯控制系统实行现场控制.     

Understanding Internet traffic streams: dragonflies and tortoises

We present the concept of network traffic streams and the ways they aggregate into flows through Internet links. We describe a method of measuring the size and lifetime of Internet streams, and use this method to characterize traffic distributions at two different sites. We find that although most streams (about 45 percent of them) are dragonflies, lasting less than 2 seconds, a significant number of streams have lifetimes of hours to days, and can carry a high proportion (50-60 percent) of the total bytes on a given link. We define tortoises as streams that last longer than 15 minutes. We point out that streams can be classified not only by lifetime (dragonflies and tortoises) but also by size (mice and elephants), and note that stream size and lifetime are independent dimensions. We submit that ISPs need to be aware of the distribution of Internet stream sizes, and the impact of the difference in behavior between short and long streams. In particular, any forwarding cache mechanisms in Internet routers must be able to cope with a high volume of short streams. In addition ISPs should realize that long-running streams can contribute a significant fraction of their packet and byte volumes-something they may not have allowed for when using traditional "flat rate user bandwidth consumption" approaches to provisioning and engineering.     

Efficient Internet traffic delivery over wireless networks

The high demand for wireless Internet connectivity has driven the development of highly efficient radio link technologies. However, their performance can be compromised by inadvertent interactions with the higher-layer TCP flow control protocol. Maximizing the performance of wireless links requires that mechanisms operating at every layer of the protocol stack interact efficiently. This article provides a brief tutorial of some of these radio link enhancements. It then outlines how higher-layer flow control protocols should behave, and provides techniques for taming the behavior of TCP, to ensure that the performance of lower-layer enhancements is not compromised.     

Extremal shape-controlled traffic patterns in high-speed networks

We consider a variable bit-rate connection with a deterministically shaped random traffic process, as specified by communications networking standards. Regarding randomness, we assume no restricted model other than the natural requirement that the process be stationary and ergodic. Given only the shape parameters, we consider the open problem of determining the maximum service bandwidth required to achieve a given bound on the probability that the packet-transfer delay exceeds a certain threshold. The shape parameters together with a probabilistic bound on the packet-transfer delay define a variable bit-rate “channel”; an equivalent problem is to determine the “capacity” of this channel. To this end, we consider a queue with a constant service rate and a shaped arrival process and obtain tight bounds on queue occupancy and queueing delay. In particular, we describe that traffic pattern (among all stationary-ergodic and deterministically constrained arrival processes) which achieves the probabilistic bound     

Identifying file-sharing P2P traffic based on traffic characteristics

This article focuses on identifying file-sharing peer-to-peer （P2P） （such as BitTorrent （BT）） traffic at the borders of a stub network. By analyzing protocols and traffic of applications, it is found that file-sharing P2P traffic of a single user differs greatly from traditional and other P2P （such as QQ） applications＇ traffic in the distribution of involved remote hosts and remote ports. Therefore, a method based on discreteness of remote hosts （RHD） and discreteness of remote ports （RPD） is proposed to identify BT-like traffic. This method only relies on flow information of each user host in a stub network, and no packet payload needs to be monitored. At intervals, instant RHD for concurrent transmission control protocol and user datagram protocol flows for each host are calculated respectively through grouping flows by the stub network that the remote host of each flow belongs to. On given conditions, instant RPD are calculated through grouping flows by the remote port to amend instant RHD. Whether a host has been using a BT-like application or not can be deduced from instant RHD or average RHD for a period of time. The proposed method based on traffic characteristics is more suitable for identifying protean file-sharing P2P traffic than content-based methods Experimental results show that this method is effective with high accuracy.     

A parameterizable methodology for Internet traffic flow profiling

We present a parameterizable methodology for profiling Internet traffic flows at a variety of granularities. Our methodology differs from many previous studies that have concentrated on end-point definitions of flows in terms of state derived from observing the explicit opening and closing of TCP connections. Instead, our model defines flows based on traffic satisfying various temporal and spatial locality conditions, as observed at internal points of the network. This approach to flow characterization helps address some central problems in networking based on the Internet model. Among them are route caching, resource reservation at multiple service levels, usage based accounting, and the integration of IP traffic over an ATM fabric. We first define the parameter space and then concentrate on metrics characterizing both individual flows as well as the aggregate flow profile. We consider various granularities of the definition of a flow, such as by destination network, host-pair, or host and port quadruple. We include some measurements based on case studies we undertook, which yield significant insights into some aspects of Internet traffic, including demonstrating (i) the brevity of a significant fraction of IP flows at a variety of traffic aggregation granularities, (ii) that the number of host-pair IP flows is not significantly larger than the number of destination network flows, and (iii) that schemes for caching traffic information could significantly benefit from using application information     

Modeling Internet backbone traffic at the flow level

Our goal is to design a traffic model for noncongested Internet backbone links, which is simple enough to be used in network operation, while being as general as possible. The proposed solution is to model the traffic at the flow level by a Poisson shot-noise process. In our model, a flow is a generic notion that must be able to capture the characteristics of any kind of data stream. We analyze the accuracy of the model with real traffic traces collected on the Sprint Internet protocol (IP) backbone network. Despite its simplicity, our model provides a good approximation of the real traffic observed in the backbone and of its variation. Finally, we discuss the application of our model to network design and dimensioning.     

Multimedia traffic characteristics in broadband networks

It is pertinent to develop a set of simple parameters that can best characterize the variability and the statistical correlations of the packet arrival process. These parameters are then used by the network to allocate its resources among the different users in order to avoid congestion and maintain a predefined quality of service (QOS) for each user. The traffic characterization and modeling of the real-time bursty traffic, mainly voice and video traffic sources, using statistical methods are described. It is shown that the variability of the variance of the sum of consecutive packet interarrival times leads to significant queuing delays and therefore is a major cause of congestion in broadband networks     

Utility-based rate control in the Internet for elastic traffic

In a communication network, a good rate allocation algorithm should reflect the utilities of the users while being fair. We investigate this fundamental problem of achieving the system optimal rates in the sense of maximizing aggregate utility, in a distributed manner, using only the information available at the end hosts of the network. This is done by decomposing the overall system problem into subproblems for the network and for the individual users by introducing a pricing scheme. The users are to solve the problem of maximizing individual net utility, which is the utility less the amount they pay. We provide algorithms for the network to adjust its prices and the users to adjust their window sizes such that at an equilibrium the system optimum is achieved. Further, the equilibrium prices are such that the system optimum achieves weighted proportional fairness. It is notable that the update algorithms of the users do not require any explicit feedback from the network, rendering them easily deployable over the Internet. Our scheme is incentive compatible in that there is no benefit to the users to lie about their utilities     

“互联网＋”智能交通管理系统设计

“互联网＋”是当前的潮流所在,大势所趋。“互联网＋”将给传统的智能交通管理带来冲击与改革、关键是模式改革,就是说,从传统的管理模式,变革为服务模式。智能交通是提升安全性、保证自由通行和减少环境影响的统一整体。为了实现这一目标将所有交通方式进行有效连接是非常重要的。     

Research of the traffic characteristics for the real time online traffic classification

Aiming at the hysteretic characteristics of classification problem existed in current internet traffic identification field,this paper investigates the traffic characteristic suitable for the on-line traffic classification,such as quality of service (QoS).By the theoretical analysis and the experimental observation,two characteristics (the ACK-Len ab and ACK-Len ba) were obtained.They are the data volume which first be sent by the communication parties continuously.For these two characteristics only depend on data’s total length of the first few packets on the flow,network traffic can be classified in the early time when the flow arrived.The experiment based on decision tree C4.5 algorithm,with above 97% accuracy.The result indicated that the characteristics proposed can commendably reflect behavior patterns of the network application,although they are simple.     

混合传播方式Ad hoc无线网络的容量研究

提出一种混合传播方式Ad hoc网络容量研究的方法,通过比较各传播方式在其相应规模下的容量确定主导传播方式并得出网络总容量。并以单播和多播混合传播为例,研究在基于多跳、MIMO和层次化合作情况下的主导传播方式和网络总容量。当该混合网络中单播的结节过半时,由多播传播方式确定网络的总容量。