End-to-end performance of 10-gigabit Ethernet on commodity systems

Apart form the success in local-area networks (LANs) and system-area networks and anticipated success in metropolitan and wide area networks (MANs and WANs), Ethernet continues to evolve to meet the increasing demands of packet-switched networks. Although the recently ratified 10-Gigabit Ethernet standard differs from earlier Ethernet standards, primarily in that 10GbE operates only over fiber and only in full-duplex mode, the differences are largely superficial. More importantly, l0GbE does not make obsolete current investments in network infrastructure. The 10GbE standard ensures interoperability not only with existing Ethernet but also with other networking technologies such as Sonet, thus paving the way for Ethernets expanded use in MANs and WANs. The world's first host-based 10GbE adapter, officially known as the Intel PRO/10GbE LR server adapter, introduces the benefits of l0GbE connectivity into LAN and system-area network environments, thereby accommodating the growing number of large-scale cluster systems and bandwidth-intensive applications, such as imaging and data mirroring. The 10GbE controller is optimized for servers that use the I/O bus backplanes of the peripheral component interface (PCI) and its higher speed extension, PCI-X.     

嵌入式系统软件开发中的通信协议研究

In the course of software developing of embedded system, we usually use the remote debugger, which needs connection and communication between the host and target through the serial port,parallel port or Ethernet. Thus some effective and reliable communication protocol is eagerly needed. The paper presents a new communication protocol called EDP (Embedded Debugger Protocol)in embedded software developing. This protocol is proven successful on Intel Assabet(SA-1110).     

嵌入式数据包捕获器的设计与实现

为了结合物理对象进行网络管理系统的研究,构建了一个嵌入式数据包捕获器.在基于Intel Xscale PXA255处理器的嵌入式硬件系统上,移植并安装了Biob和嵌入式Linux操作系统,构成了嵌入式网络服务器节点.该节点既能通过串口与物理对象直接通信,又利用Libpcap函数库实现对网络中各数据包的捕获与过滤.这对于日益发展的网络通信在嵌入式设备中的应用有很好的借鉴意义.     

A priority media access control protocol for video communication support on CSMA/CD LANs

Real-time multimedia communication applications demand performance requirements which differ significantly from conventional data communication applications. Current local area networks (LANs) provide efficient transport for bursty data traffic; however, they cannot necessarily provide quality of service guarantees for real-time communications. In this work we introduce and investigate an experimental priority protocol for supporting real-time communication on Ethernet, a popular implementation of multiple-access broadcast bus LANs. We examine the new protocol, known as Priority Mode-CSMA/CD (PM-CSMA/CD), providing a high priority (HP) class with CSMA/CD employed for standard priority (SP) traffic. PM-CSMA/CD performance is examined through computer simulation of videotelephony workstations operating over the shared bus LAN. Over all observed traffic conditions, the priority protocol provides performance satisfying real-time packet transport requirements of audio and video streams. The primary advantage of our protocol over similar priority schemes is its physical layer compatibility with standard CSMA/CD. The protocol also provides improved channel utilization with increasing high priority load, with no penalty in SP class performance at low to medium network loads.     

可用于云制造环境的新型现场总线协议

针对云制造模式中底层物理资源属性难以接入云制造平台的问题,提出一种云现场总线协议Cloud_Field_Bus以及与之配合的多协议转换模块。以标准以太网协议为基础,优化其数据链路层及上层协议,实现海量数据信息可靠传输;多协议转换模块实现多种协议接口的透明接入。仿真实验测试Cloud_Field_Bus协议的报文循环时间、编码效率以及误码率,实验结果表明,Cloud_Field_Bus协议信息表达的高效性和传输可靠性,在一定程度上解决了云制造底层物理资源接入困难的问题。     

基于嵌入式Web的网络监控系统

针对加油站分布广、通信协议不统一难于实现集成监控,提出了一种基于嵌入式Web的集成监控系统。基于Intel Xscale IXP-422 RISC CPU的嵌入式Web服务器,通过工业以太网互联现场各加油站服务器,完成对现场设备的集成监控。Web浏览控制采用Apache+Html+PHP的方案实现。测试结果表明,该系统安全级别高、实时性好、抗干扰能力强、环境适应性好。     

基于IPv6的UDP通信的实现

IPv6是为了克服现在IPv4协议的缺陷而设计的下一代因特网协议。随着Internet的飞速发展,IPv6(Internet Pro-tocol Version 6)必然会取代IPv4,开发支持IPv6的网络应用程序已经迫在眉睫。文中首先对IPv6进行了简介;然后介绍了UDP的通信原理I、Pv6下Socket地址结构和IPv6下Socket函数,并给出了在IPv6下基于无连接的Socket的客户机/服务器模型和利用UDP协议进行网络通信的方法;最后实现了在IPv6协议下服务器端和客户端之间数据信息的传输,相信对今后开发基于IPv6的大型网络应用程序会有极大的帮助。     

PROFIBUS-DP现场总线协议优化

针对工业企业对传榆控制协议高速和高可靠性的需求,提出了一种利用以太网通信技术对PROFIBUS.DP总线协议进行优化的方案,通过定义物理层、数据链路层协议及创建EDDL的功能实现DP以太网.新构造的DP以太网通信协议可以支持比原协议更高的通信带宽,而且还能兼容基于PROFIBUS-DP上层协议的各种进程.通过对比分析基于DP以太网协议和PROFIBUS-DP协议的通信网络的报文循环时间和报文编码效率可知,该协议解决了PROFIBUS-DP协议支持的通信速率较低的问题,实现了对该协议的优化.     

An efficient design and validation technique for secure handover between 3GPP LTE and WLANs systems

Future generations wireless systems, which integrate different wireless access networks together, will support a secured seamless mobility and a wide variety of applications and services with different quality of service (QoS) requirements. Most of the existing re-authentication protocols during vertical handover still have certain limitations such as man in the middle, eavesdropping and session hijacking attacks, and unacceptable delay for real time applications. In this article, we propose two re-authentication schemes to secure handover between 3GPP LTE and WLANs systems: Initial Handover Re-authentication Protocol, and Local Re-authentication Protocol. The second proposed protocol is executed locally in a WLAN network without contacting the authentication server of the home network for credentials verification. In fact, after a successful execution of the Initial Handover Re-authentication Protocol, the local key (LK) is shared between USIM and the authentication server of the WLAN. It is then used for securing handover and traffic in WLAN networks. Performance evaluation results obtained using simulation analysis show that the proposed re-authentication protocol enhances handover parameters such as handover latency, handover blocking rate and packet loss rate. Additionally, the proposed enhanced fast re-authentication protocol has been modeled and verified using the software AVISPA and is found to be safe.     

一种可重构以太网数据包解析器中可重构单元的设计

不停变化的网络协议标准和用户定制化网络业务需求要求交换机硬件具有更高的灵活性。在此背景下,提出了一种能够通过软件编程定义协议解析规则的以太网交换机芯片数据包解析器基本处理单元,具有高性能且高灵活性的优点,通过灵活配置硬件解析逻辑和查找表内容,定义对数据包包头内容的提取、查找、匹配、动作等解析过程,从而支持对不同种类的协议解析任务,其由2类基本结构的串联或并联组合而成,这样可以根据需要进行硬件资源裁剪。基于该可重构基本处理单元,可以构成可重构报文解析器,支持自定义协议及未知协议的解析。主要介绍了该可重构基本处理单元的结构,并介绍了基于该基本处理单元的解析器架构的实现方法。采用40 nm工艺综合后的评估结果显示,该基本单元电路最高工作时钟频率可以达到240 MHz,基于该基本处理单元结构实现的支持4层常用以太网协议解析的解析器每秒可处理2.4亿个数据包。该可重构基本处理单元所用存储资源共计87.98 Kb,设计规模约147万门。     

Long-haul secure data transfer using hardware-assisted GridFTP

Extreme-scale scientific collaborations require high-performance wide-area end-to-end data transports to enable fast and secure transfer of high data volumes among collaborating institutions. GridFTP is the de facto protocol for large-scale data transfer in science environments. Existing predominant network transport protocols such as TCP have serious limitations that consume significant CPU power and prevent GridFTP from achieving high throughput on long-haul networks with high latency and potential packet loss, reordering and jitter. On the other hand, protocols such as UDT that address some of the TCP shortcomings demand high computing resources on data transfer nodes. These limitations have caused underutilization of existing high-bandwidth links in scientific and collaborative grids. To address this situation, we have enhanced Globus GridFTP, the most widely used GridFTP implementation, by developing transport offload engines such as UDT and iWARP on SmartNIC, a programmable 10GbE network interface card (NIC). Our results show significant reduction in server utilization and full line-rate sustained bandwidth in high-latency networks, as measured for up to 100 ms of network latency. In our work, we also offload OpenSSL on SmartNIC to reduce host utilization for secure file transfers. The offload engine can provide line-rate data channel encryption/decryption on top of UDT offload without consuming additional host CPU resources. Lower CPU utilization leads to increased server capacity, which allows data transfer nodes to support higher network and data-processing rates. Alternatively, smaller or fewer DTNs can be used for a particular data rate requirement.     

Statistical real-time communication over Ethernet

In order to realize real-time communication over Ethernet or fast Ethernet, one must be able to bound the medium access time within an acceptable limit. The multiple access nature of Ethernet makes it impossible to guarantee a deterministic medium access time (hence, packet-delivery deadlines) to individual stations. However, one can bound the medium access time statistically by limiting the packet-arrival rate at the medium access control (MAC) layer. While considering automated manufacturing systems as the main target application, this paper addresses the connection admission control (CAC) problem for statistically bounding the medium access time of Ethernet. Specifically, a packet is guaranteed to have a medium access time smaller than a predefined bound with a certain probability if the instantaneous packet-arrival rate is kept below a certain threshold. Through a mathematical analysis, we first derived such a threshold. In order to keep the packet-arrival rate under the given threshold, we developed and installed middleware which 1) resides between the transport layer and the Ethernet datalink layer, and 2) smooths packet streams between them. The implementation of this middleware requires only a minimal change in the OS kernel without modification to the current standard of Ethernet MAC protocol or TCP or UDP/IP stack. In order to solve the CAC problem, we derived the probability of transmitting a packet successfully upon each trial by modeling the MAC protocol, 1-persistent CSMA/CD, and the collision resolution protocol inary exponential backoff - of Ethernet. Our in-depth simulation results have shown this analytic model to provide a reasonably accurate estimate of packet-loss (or deadline-miss) ratio over fast Ethernet. Finally, we implemented the middleware on the Linux OS, experimentally demonstrating the effectiveness of our approach in providing real-time communication over Ethernet.     

A study of adaptive forward error correction for wireless collaborative computing

This paper addresses the problem of reliably multicasting Web resources across wireless local area networks (WLANs) in support of collaborative computing applications. An adaptive forward error correction (FEC) protocol is described, which adjusts the level of redundancy in the data stream in response to packet loss conditions. The proposed protocol is intended for use on a proxy server that supports mobile users on a WLAN. The software architecture of the proxy service and the operation of the adaptive FEC protocol are described. The performance of the protocol is evaluated using both experimentation on a mobile computing testbed as well as simulation. The results of the performance study show that the protocol can quickly accommodate worsening channel characteristics in order to reduce delay and increase throughput for reliable multicast channels.     

Building local area networks to Ethernet specification

Digital, Intel and Xerox (DIX) have published an Ethernet standard that specifies the physical and datalink layers of Ethernet, one of the two types of local area networks likely to be widely used in industrial and commerical applications. The publication of the DIX specification is a commercial exercise intended to encourage the implementation and marketing of Ethernet-compatible network elements. In the Computer Science Department at Strathclyde University the authors followed this specification to some extent in implementing an Ethernet-style local network called Strathnet. In their implementation, the physical and datalink layers are built into microprocessor-based network-access units by means of which computers, terminals and other devices are connected to Strathnet. The paper discusses the feasibility and desirability of building local networks to the standards of the Ethernet specification and in the light of this discussion outlines the author's approach in the implementation of Strathnet.     

SeaHttp: A Resource-Oriented Protocol to Extend REST Style for Web of Things

Web of Things （WoT） makes it possible to connect tremendous embedded devices to web in Representational State Transfer （REST） style. Some lightweight RESTful protocols have been proposed for the WoT to replace the HTTP protocol running on embedded devices. However, they keep the principal characteristic of the REST style. In particular, they support one-to-one requests in the client-server mode by four standard RESTful methods （GET, PUT, POST, and DELETE）. This characteristic is however inconsistent with the practical networks of embedded devices, which typically perform a group operation. In order to meet the requirement of group communication in the WoT, we propose a resource-oriented protocol called SeaHttp to extend the REST style by introducing two new methods, namely BRANCH and COMBINE respectively. SeaHttp supports parallel processing of group requests by means of splitting and merging them. In addition SeaHttp adds spatiotemporal attributes to the standard URI for naming a dynamic request group of physical resource. Experimental results show that SeaHttp can reduce average energy consumption of group communication in the WoT by 18.5%, compared with the Constrained Application Protocol （CoAP）.     

CC-NUMA架构下4路龙芯3B服务器设计与实现

针对特定领域中服务器的高性能计算、高带宽通信以及自主可控需求,在分析龙芯3B3000处理器架构特点的基础上,设计了基于CC NUMA并行处理架构的4路龙芯3B3000高性能服务器核心模块,通过使用TOE芯片提高了网络响应效率,同时大幅降低了10G以太网接口对处理器资源的占用消耗,有效提高了服务器的综合性能。通过测试验证,该服务器能够实现高效的并行计算能力和10G以太网通信能力,且国产元器件种类占比和数量占比均可达95%以上。     

Performance analysis of Ethernet Powerlink networks for distributed control and automation systems

Industrial communication networks are a key element for developing advanced distributed control and automation systems. On the one hand, high performance and low costs are generally required to cope with more and more demanding application requirements, while, on the other hand, real-time capabilities are often needed in an increasing number of automation scenarios.Communication solutions based on Ethernet technologies are becoming popular in many industrial and factory environments and a number of soft/hard real-time competing products have been proposed in the last few years.This paper focuses on the Ethernet Powerlink standard, in general, and on some of its real-time characteristics, in particular. In fact, we present some basic results concerning both cyclic and acyclic real-time traffic in Ethernet Powerlink networks, obtained by extensive simulation, which can be used as a basic step for a better understanding of the real-time behavior of this protocol.     

Performance-based path determination for interprocessorcommunication in distributed computing systems

The different types of messages used by a parallel application program executing in a distributed computing system can each have unique characteristics so that no single communication network can produce the lowest latency for all messages. For instance, short control messages may be sent with the lowest overhead on one type of network, such as Ethernet, while bulk data transfers may be better suited to a different type of network, such as Fibre Channel or HIPPI. This work investigates how to exploit multiple heterogeneous communication networks that interconnect the same set of processing nodes using a set of techniques we call performance-based path determination (PBPD). The performance-based path selection (PBPS) technique selects the best (lowest latency) network among several for each individual message to reduce the communication overhead of parallel programs. The performance-based path aggregation (PBPA) technique, on the other hand, aggregates multiple networks into a single virtual network to increase the available bandwidth. We test the PBPD techniques on a cluster of SGI multiprocessors interconnected with Ethernet, Fibre Channel, and HiPPI networks using a custom communication library built on top of the TCP/IP protocol layers. We find that PBPS can reduce communication overhead in applications compared to using either network alone, while aggregating networks into a single virtual network can reduce communication latency for bandwidth-limited applications. The performance of the PBPD techniques depends on the mix of message sizes in the application program and the relative overheads of the networks, as demonstrated in our analytical models     

Usefulness of adaptive load sharing for parallel processing on networks of workstations

Networks of workstations (NOWs) can be used for parallel processing by using public domain software like PVM. However, NOW-based parallel processing suffers from node heterogeneity, background load variations, and high-latency, low-bandwidth communication network. Previous studies on load sharing in NOW-based systems have indicated that, for applications using the work-pile model, a simple load sharing scheme in which the master process gives a fixed amount of work to the slave processes performs as well as any other, more complex schemes. In this paper, we propose a new adaptive load sharing scheme and evaluate its performance using a Pentium-based NOW machine. The communication network used in the system consists of the standard 10 Mbps Ethernet and the 100 Mbps fast Ethernet. We use both these networks to study their impact on the performance of our new policy. The results presented here indicate that the new policy is useful for computation-intensive applications. Copyright © 1999 John Wiley & Sons, Ltd.     

以太网上多连接通信协议的设计,实现及管理

以太网上多个站点之间以永久连接方式进行通信。本文设计并实现其通信协议。该协议采用广播分组同时对多连接进行应签，对加续ＡＲＱ和选择ＡＲＱ进行了综合，简化了协议处理和缓冲区管理、提高了以太网胶卵利用率。