Game Theoretic Stochastic Routing for Fault Tolerance and Security in Computer Networks

We introduce the game-theoretic stochastic routing (GTSR) framework, a proactive alternative to today's reactive approaches to route repair. GTSR minimizes the impact of link and router failure by 1) computing multiple paths between source and destination and 2) selecting among these paths randomly to forward packets. Besides improving fault tolerance, the fact that GTSR makes packets take random paths from source to destination also improves security. In particular, it makes connection eavesdropping attacks maximally difficult as the attacker would have to listen on all possible routes. The approaches developed are suitable for network layer routing, as well as for application layer overlay routing and multipath transport protocols such as the stream control transmission protocol (SCTP). Through simulations, we validate our theoretical results and show how the resulting routing algorithms perform in terms of the security/fault-tolerant/delay/throughput trade-off. We also show that a beneficial side effect of these algorithms is an increase in throughput, as they make use of multiple paths.     

Architectural Breakdown of End-to-End Latency in a TCP/IP Network

Adoption of the 10GbE Ethernet standard as a high performance interconnect has been impeded by two important performance-oriented considerations: (1) processing requirements of common protocol stacks and (2) end-to-end latency. The overheads of typical software based protocol stacks on CPU utilization and throughput have been well evaluated in several recent studies. We focus on end-to-end latency and present a detailed characterization across typical server system hardware and software stack components. We demonstrate that application level end-to-end one-way latency with a 10GbE connection can be as low as 10 μs for a single isolated request in a standard Linux network stack. The paper analyzes the components of the latency and discusses possible significant variations to the components under realistic conditions. We found that methods that optimize for throughput can significantly compromise Ethernet based latencies. Methods to pursue reducing the minimum latency and controlling the variations are presented.     

A root cause analysis toolkit for TCP

TCP is the most widely used protocol for data transfer over the Internet and for most applications the performance metric of interest is throughput. Identifying the reasons for the throughput limitation of an observed connection is a complex task. We present a set of techniques, called the TCP root cause analysis toolkit, that allow users to determine from a passively captured packet trace the primary cause for the throughput limitation. We present the details of the toolkit and its validation and apply the toolkit to carry out a case study of ADSL traffic.     

Stabilizing transport dynamics of control channels over wide-area networks

The next generation large-scale computing applications require network support for interactive visualization, computational steering and instrument control over wide-area networks. In particular, these applications require stable transport streams over wide-area networks, which are not adequately supported by current transport methods. We propose a new class of protocols capable of stabilizing a transport channel at a specified throughput level in the presence of random network dynamics based on the classical Robbins–Monro stochastic approximation approach. These protocols dynamically adjust the window size or sleep time at the source to achieve stable throughput at the destination. The target throughput typically corresponds to a small fraction of the available connection bandwidth. This approach yields provably probabilistically stable protocols as a consequence of carefully adjusted step sizes. The superior and robust stabilization performance of the proposed approach is extensively evaluated in a simulated environment and further verified through real-life implementations and deployments over both Internet and dedicated connections under disparate network conditions in comparison with existing transport methods.     

A simulation-based study of TCP dynamics over HFC networks

New broadband access technologies such as hybrid fiber coaxial (HFC) are likely to provide fast and cost effective support to a variety of applications including video on demand (VoD), inter-active computer games, and Internet-type applications such as Web browsing, ftp, e-mail, and telephony. Since most of these applications use TCP as the transport layer protocol, the key to their efficiency largely depends on TCP protocol performance.We investigate the performance of TCP in terms of effective throughput in an HFC network environment using different load conditions and network buffer sizes. We find that TCP experiences low throughput as a result of the well-known problem of ACK compression. An algorithm that controls ACK spacing is introduced to improve TCP performance.     

Simulation methodology and performance analysis of network coding based transport protocol in wireless big data networks

The Multi-Path, Multi-Hop (MPMH) communications have been extensively used in wireless network. It is especially suitable to big data transmissions due to its high throughput. To provide congestion and end-to-end reliability control, two types of transport layer protocols have been proposed in the literature: the TCP-based protocols and the rateless coding based protocols. However, the former is too conservative to explore the capacity of the MPMH networks, and the latter is too aggressive in filling up the communication capacity and performs poorly when dealing with congestions. To overcome their drawbacks, a novel network coding scheme, namely, Adjustable Batching Coding (ABC), was proposed by us, which uses redundancy coding to overcome random loss and uses retransmissions and window size shrink to relieve congestion. The stratified congestion control strategy makes the ABC scheme especially suitable for big data transmissions. However, there is no simulation platform built so far that can accurately test the performance of the network coding based transport protocols. We have built a modular, easy-to-customize simulation system based on an event-based programming method, which can simulate the ABC-based MPMH transport layer behaviors. Using the proposed simulator, the optimal parameters of the protocol can be fine-tuned, and the performance is superior to other transport layer protocols under the same settings. Furthermore, the proposed simulation methodology can be easily extended to other variants of MPMH communication systems by adjusting the ABC parameters.     

An energy-efficient,transport-controlled MAC protocol for wireless sensor networks

In wireless sensor networks (WSNs), one major cause of wasted energy is that the wireless network interface is always on to accept possible traffic. Many medium access control (MAC) protocols therefore adopted a periodic listen-and-sleep scheme to save energy, at sacrifice of end-to-end latency and throughput. Another cause is packet dropping due to network congestion, necessitating a lightweight transport protocol for WSNs. In this paper, we suggest a transport-controlled MAC protocol (TC-MAC) that combines the transport protocol into the MAC protocol with the aims of achieving high performance as well as energy efficiency in multi-hop forwarding. Although TC-MAC also works through a periodic listen-and-sleep scheme, it lowers end-to-end latency by reserving data forwarding schedules across multi-hop nodes during the listen period and by forwarding data during the sleep period, all while increasing throughput by piggybacking the subsequent data forwarding schedule on current data transmissions and forwarding data consecutively. In addition, TC-MAC gives a fairness-aware lightweight transport control mechanism based on benefits of using the MAC-layer information. The results show that TC-MAC performs as well as an 802.11-like MAC in end-to-end latency and throughput, and is more efficient than S-MAC in energy consumption, with the additional advantage of supporting fairness-aware congestion control.     

T.120数据会议中传输连接扩展机制的剖析与评估

作为ITU-TT.120多媒体数据会议一致的网络传输协议栈,T.123引入的X.224class0传输协议严格限制其下层必须采用可靠的网络服务。这限制了不可靠网络协议及安全协议在数据会议中的使用。本文讨论了在X.224class0基础上采用协商机制的可扩展连接模型,并就其协商连接的方式和性能进行了剖析和评估,借以推广和拓展数据会议系统在安全及不可靠数据传输协议应用等方面的研究。     

From multimedia models to multimedia transport protocols

This paper presents a new protocol architecture for distributed multimedia systems which includes a new and general protocol layer for the transport of multimedia objects. The proposed protocols are based on the use of two extended timed and time Petri net models that specify the synchronisation requirements of multimedia applications. After presenting these two formal models, it is shown how they have been used to design the general multimedia architecture whose transport layer is based on the concept of a partial order connection, an extension of the classical connection oriented (e.g., TCP) and connectionless (e.g., UDP) transmission concepts.     

A Secure TCP Connection Migration Protocol to Enable the Survivability of Client-Server Applications Under Malicious Attack

Transmission Control Protocol (TCP) connection migration has been previously proposed to allow for the mobility of servers. In this paper we revisit TCP connection migration for purposes of server survivability against malicious denial-of-service attacks. We present a protocol that allows an on-going TCP connection to be migrated from one server to another. This migration is performed in a secure manner such that the protocol itself cannot be exploited for malicious attacks. Further the migration can be performed even in the case where the original server is compromised. The protocol has been designed so as to allow interoperability with legacy TCP protocols. It is intended to be the transport layer foundations over which survivable applications can be built.     

Unreliable transport protocol using congestion control for high-speed networks

Currently there is no control for the real-time traffic of multimedia applications using UDP (User Datagram Protocol) in high-speed networks. Therefore, although a number of high-speed TCP (Transmission Control Protocol) protocols have been developed for gigabit-speed (or faster) links, the real-time traffic could also congest the network and result in unfairness and throughput degradation of TCP traffic. In this paper, a new unreliable transport protocol, FAST DCCP, is presented for the real-time traffic in high-speed networks. FAST DCCP is based on the DCCP protocol and adopts the FAST scheme to realize congestion control. Some modifications have been made to the mechanisms inherited from DCCP so as to let the proposed protocol can efficiently operate under a large size window. In addition, an enhanced protocol, EEFAST DCCP, using the measurements of one-way delay to dynamically adjust the window size is also proposed to improve the throughput of FAST DCCP with the effect of reverse traffic. Simulation results show that FAST DCCP not only can satisfy the requirements of real-time data delivery, but also perform well in bandwidth utilization and fairness in high-speed networks. Meanwhile, EEFAST DCCP is able to effectively conquer the throughput degradation caused by the reverse traffic.     

多路径负载均衡性能仿真分析

在网络拥塞条件下进行大数据量的文件传输时,单一传输路径会导致较长的文件下载响应时间.在计算机网络仿真平台上,设计了开放式最短路径优先(OSPF)多路径负载均衡算法,得到了文件下载响应时间及链路吞吐量等网络性能参数.仿真表明:网络层采用多路径负载均衡技术的路由协议,可以优化网络资源利用率;传输层采用用户数据报协议(UDP),则可以进一步降低文件下载响应时间,提高网络性能.     

Efficiency Analysis of the Forward Error Correction at the Transport Protocol Level

Automation and Remote Control - We propose a model of a virtual connection controlled by a transport protocol with a forward error correction mechanism in the selective and group repetition mode in...     

Parallel transport subsystem implementation for high-performance communication

Requirements of emerging applications together with rapid changes in networking technology towards gigabit speeds require new adequate transport systems. Integrated designs of transport services, protocol architecture and implementation platforms are required by forthcoming applications in high-speed network environments. The transport subsystem PATROCLOS (parallel transport subsystem for cel/ based high-speed networks) is designed with special emphasis on a high degree of inherent parallelism to allow efficient implementations on multiprocessor architectures combined with specialized hardware for very time critical functions. The paper presents the new parallel protocol architecture of PATROCLOS, an appropriate implementation architecture based on transputer networks, and performance evaluation results, which indicate high throughput values.     

Analysis of two competing TCP/IP connections

Many mathematical models exist for describing the behavior of TCP/IP (TCP: transmission control protocol) under an exogenous loss process that does not depend on the window size. The goal of this paper is to present a mathematical analysis of two asymmetric competing TCP connections where loss probabilities are directly related to their instantaneous window size, and occur when the sum of throughputs attains a given level. We obtain bounds for the stationary throughput of each connection, as well as an exact expression for symmetric connections. This allows us to further study the fairness as a function of the different round trip times. We avoid the simplifying artificial synchronization assumption that has frequently been used in the past to study similar problems, according to which whenever one connection looses a packet, the other one looses a packet as well.     

无线传感器网络动态节能信道接入协议

为了使无线传感器网络移动节点加入时能快速地建立连接并且能量消耗较低,提出一种动态、节能的信道接入控制协议DEE-MAC.该协议以一种新颖的方式在TDMA的基础上叠加了动态分簇和优先级竞争簇头机制,在移动和静止场景中,既有最低性能保障,又有较高信道利用率.仿真结果表明,有移动节点加入时,DEE-MAC协议在数据吞吐量、延时以及丢包率方面比SMAC协议都有明显改善.     

多场景的MPTCP协议性能分析研究

利用多宿主设备的多个接口实现多路径传输、获取更多的网络吞吐量是因特网协议研究的热点。IETF所关注的MPTCP协议是当前比较成熟、关键的多路径传输协议。为了测试MPTCP在当前已部署的网络环境中的性能,分别在本地测试床、Internet环境测试场景和大规模多宿主系统NorNet测试床中对MPTCP多路径传输实际吞吐量性能进行了测试和分析,测试结果表明MPTCP相对TCP虽能获得吞吐量的提高,但在非相似带宽链路的场景中其性能仍然不完善,其路径管理和传输调度策略仍需要进一步改进。     

IEEE802.16e的实时上行链路调度服务优化算法

深入分析了IEEE802.16e建议的三种实时调度服务算法：UGS、rtPS、ertPS，并在此基础上提出了一种优化的实时调度服务算法：irtPS。该优化的调度服务算法在保证变化数据率实时上行链路的延时性能基础上，最大限度地提高了实时上行链路的资源利用率。数学建模分析结果显示，在保证延时性能的前提下，该优化的调度服务算法的系统容量较IEEE802.16e建议算法的系统容量有显著增加。     

通信协议的并行机制研究

通信技术的迅速发展，通信网络所提供的带宽达到几百Ｍｂｐｓ～Ｇｂｐｓ数量级。一些应用，象多媒体通信，就能利用网络的高吞吐量。但是，目前的通信协议并不能适应高速传输的环境。运输层和其它较高层协议的处理，已成为通信系统的性能瓶颈。本文首先回顾近十年来通信环境所发生的一些变化，并分析其对运输层协议的影响；第二部分分析标准协议并行实现时的一些关键技术；最后介绍了一个运输层系统模型，该模型采用并行机制，向上提供高性能的运输层服务。     

The level of handshake required for managing a connection

A connection between two hosts across a wide-area network may consist of many sessions over time, each called an incarnation. A connection is synchronized using a connection establishment protocol, based on a handshake mechanism, to allow reliable exchange of data. This paper identifies the precise level of handshake needed under different assumptions on the nodes and on the network, using a formal model for connection management. In particular, the following parameters are studied: the size of the memory at the nodes, the information retained between incarnations, and the existence of time constraints on the network. Among the results we obtain are: (1) If both nodes have bounded memory, no incarnation management protocol exists. (2) If the nodes have unbounded memory, then a two-way handshake incarnation management protocol exists. (3) If the nodes have unbounded memory, and the server does not retain connection-specific information between incarnations, then a three-way handshake incarnation management protocol exists. On the other hand, a two-way handshake incarnation management protocol does not exist, even if some global information is retained. (4) If a bound on maximum packet lifetime (MPL) is known, then a two-way handshake incarnation management protocol exists, in which the server does not retain connection-specific information between incarnations. Received: July 1995 / Accepted: July 1997