SDH DCC管理信息通信的协议栈

本文介绍ＳＤＨＤＣＣ协议栈各层的主要内容和特征，特别是面向目标的应用层ＣＭＩＳＥ、ＲＯＳＥ、ＡＣＳＥ，网络层的路由参数以及数据键路层的ＬＡＰＤ。并给出了各层ＰＤＵ间的对应关系。最后举出两种网络单元中协议栈配置的实例。     

Performance Evaluation of Multireject, Selective Reject, and Other Protocol Enhancements

This study compared the effects on performance of four features of the LAPB and LAPD protocols. LAPB is the link level for the X.25 protocol, and LAPD is the link level for the ISDN "D" signaling channel. The features were: multireject in which additional reject or selective reject frames can be retransmitted under certain conditions, selective reject in which an entity can request selected frames to be retransmitted, the null information frame (NIF) with which additional control frames are sent to help detect missing frames, and multiple service access points (SAP's) in which several link-level protocol handlers are multiplexed on the same physical link (a feature unique to LAPD). Results indicate that the current standard LAPB/D protocol with multireject is the preferred protocol. Selective reject generally performed worse than the standard protocol, and offered improvement only with complex and expensive enhancements. The NIF feature yielded a virtually unnoticeable performance improvement. Multi-SAP introduced a virtually unnoticeable impairment when it was used to carry the same traffic load as a single SAP.     

基于ATM虚拟局域网的网络拓扑搜索

动态显示网络系统的拓扑图是网络管理系统的基本功能,目前常见的拓扑搜索算法大部分都是基于网络层的,不能对链路层的动态网络拓扑进行搜索且不能发现和管理虚拟网。提出一种利用SNMP协议、ICMP 协议和ARP协议三种协议相结合的网络拓扑搜索算法,发现ATM网络的链路层网络拓扑和提取ATM虚拟网的配置信息。最后,以哈工大通信所的某一子网（ATM虚拟局域网）为例,对此算法进行了验证。     

Wireless LANs and mobile networking: standards and futuredirections

The emerging widespread use of wireless LAN systems together with the users' desire for such systems to interoperate has created a requirement for standards. Many standards bodies are currently defining standards for wireless systems that relate to different layers of the networking protocol stack. Of these, two influential physical and data link layer standards, IEEE 802.11 and the European HIPERLAN, are described. The article then considers the network layer by discussing extensions that are being made to the widely used Internet protocol (IP) to deal with mobility (wired or wireless). The final standards that are discussed relate to wireless link management. The article concludes by speculating on future directions for wireless LAN systems     

CCITT/ANSI voice packetization protocol

This paper introduces the packetized voice protocol G.PVNP/T1.PVP which is being standardized in both the CCITT and T1Y1. At layer 2, G.PVNP/T1.PVP extends the ISDN LAPD protocol to include packetized voice, thereby potentially allowing the integration of voice and data traffic. Layer 3 specifies procedures to deal with voice-band data traffic and to handle channel-associated signalling.     

ISDN网络终端NT2的设计与实现

详细报告一种ＩＳＤＮ的第二类网络终端设备ＮＴ２的硬件和软件设计与实现,包括硬件总体设计方案,基本速率接口硬件模块设计,交换模块硬件设计,时钟模块的硬件设计,其群速率接口模硬件设计。物理层软件设计,ＬＡＰＤ协议软件设计,Ｄ信道网络层协议软件设计。     

一种基于卫星IP网络的数据链路层协议

通过分析卫星通信网络发展趋势,阐述卫星网络中现有的数据链路层协议,梳理归纳卫星网络的特点及影响,提出了一种新型卫星网络数据链路层协议(New Satellite Link Protocol,NSLP)。分析对比表明,该协议能够有效降低链路层报头开销,提高信息传输效率。在实际应用中,新型协议具有能够简化数据链路层的功能,有与TCP/IP协议兼容性好、与IP协议耦合度高、节约星上资源等诸多优点,有利于卫星IP网络整体性能的有效提升。     

Examination of the applicability of router and bridging techniques

Bridges are compared to routers from a number of perspectives. Routers are systems that interconnect networks based on information contained in layer 3, the networking layer, of the Open Systems Interconnection (OSI) model. Bridges use layer 2 (data link layer) information to determine whether packets should be passed from one network to another. This type of interconnection strategy use node address data only and thus is independent of the protocol used for OSI layer 3 and above. Processing requirements of bridges and routers are compared, highlighting the more complex processing needs of the latter. The greater functionality and flexibility of routing, which accompanies this increased complexity, is discussed. In particular, the focus is on the ability of routers to interconnect different local area network techniques, deal with heavy traffic, and control topology     

Relation of User-Perceived Response Time to Error Measurements on ISDN Data Links

The LAPD link-level protocol was used to interchange messages on a computer-simulated link. The link was subjected to random errors generated with the Gilbert error-producing model. Tabulations were made of the delays encountered in sending and acknowledging messages, and of facility statistics such as error-free seconds. Objectives are 1) provide quantitative relationships between facility measurements and user-perceived performance on a data circuit, and 2) determine which measurements correlate best with observed performance. Major conclusions include: an interval of one second is recommended for facility measurements, as shorter interval measurements such as bit-error ratio are strongly distorted by certain types of errors; error-free seconds (EFS) correlates poorly with link response time performance; a new measure, the sum of squares of errored-second sequences (SQUESS), yields better correlation,     

SSCOP信令传输时延分析与检测

SSCOP协议是ATM宽带网络信令系统数据链路层的一部分,SSCOP信令链路为ATM网络元素之间提供可靠的信令信息传输。信令链路传输时延是ATM网络传输质量的一个重要参数,SSCOP协议的很多重要参数的取值都依赖于传输时延的大小。介绍一种SSCOP信令链路传输时延的检测方法,通过构造一种特殊的SSCOP报文来测试信令网络的传输质量,并计算信令报文的传输时延。对提高ATM信令系统的网络质量和优化SSCOP协议参数具有一定的现实意义。     

无线ATM通信网的关键技术与研究现状

本文介绍支持多媒体业务的无线ＡＴＭ通信网的关键技术，如协议分层模型与网络结构、物理层技术、多址访问控制协议、数据链路控制协议和网络管理与控制技术等，并结合国内外的研究现状进行了论述。     

Scheduling structure to achieve inter-layer optimisation inwireless IP networks

An inter-layer scheduling structure that achieves a coupling between the IP and data link layer is proposed. Based upon the QoS requirements from the network layer and the available resources at link layer the optimal bearer is selected. The combination of information from different layers in the protocol stack allows for a more optimised and accurate control of the traffic flows with different QoS requirements     

A Cross-Layer (Layer 2 + 3) Handoff Management Protocol for Next-Generation Wireless Systems

Next-generation wireless systems (NGWS) integrate different wireless networks, each of which is optimized for some specific services and coverage area to provide ubiquitous communications to the mobile users. It is an important and challenging issue to support seamless handoff management in this integrated architecture. The existing handoff management protocols are not sufficient to guarantee handoff support that is transparent to the applications in NGWS. In this work, a cross-layer (Layer 2 + 3) handoff management protocol, CHMP, is developed to support seamless intra and intersystem handoff management in NGWS. Cross-layer handoff management protocol uses mobile's speed and handoff signaling delay information to enhance the handoff performance of Mobile IP that is proposed to support mobility management in wireless IP networks. First, the handoff performance of Mobile IP is analyzed with respect to its sensitivity to the link layer (Layer 2) and network layer (Layer 3) parameters. Then, a cross-layer handoff management architecture is developed using the insights learnt from the analysis. Based on this architecture, the detailed design of CHMP is carried out. Finally, extensive simulation experiments are carried out to evaluate the performance of CHMP. The theoretical analysis and simulation results show that CHMP significantly enhances the performance of both intra and intersystem handoffs.     

HDLC协议处理芯片在微机查号系统中的应用

在目前的数字通信系统或网络设计中,普遍采用了HDLC协议,该协议是在同步网上传输数据时需要遵守的数据链路层协议,也是一种面向比特位的数据链路控制协议。HDLC协议的实现方式有两种,分别是软件实现和硬件实现。本文介绍了HDLC协议的特点,采用硬件实现的方法,及采用HDLC协议处理芯片MT8952B设计和实现了在微机查号系统中的数据传输,并对采用此方法实现数据通信的优点进行了阐述。     

无线传感器网络的能源策略分析

由随机分布的集成有传感器、数据处理单元和通信模块的微小节点通过自组织的方式构成的无线传感器网络在工业、农业、商业、军事、医疗保健等领域有着广泛的应用，由于其通常运行在人不能或不便接近的环境，能源无法替代，因此，设计有效的策略延长网络的生命周期成为无线传感器网络的核心问题。本文从网络的物理层、数据链路层、网络层及系统能量管理平面讨论了节能的策略，指出ID协议，GRAd协议值得进一步关注，能耗的考虑应贯穿网络设计的每一环节。     

基于IP协议的卫星组网通信关键技术研究

早期卫星组网一般采用地球同步卫星(GEO)作为中继器，而现在的卫星宽带信息网则是通过星间链路(ISL)实现相邻卫星之间直接通信，研究宽带卫星组网技术对于加快我国信息基础设施建设具有极其重要的作用。本首先介绍卫星通过星间链路组网通信的系统模型，然后分析卫星网络IP系统的协议堆栈，并对卫星网络TCP/IP协议各层采用的接口和协议、基本功能、工作方式等进行详细研究，最后对卫星组网通信中涉及的物理层、数据链路层和网络层的关键技术逐一进行了探讨。     

Intelligent home systems

The home automation system module, communications standards developed in the US by the Electronic Industry Association (EIA) and known as the Consumer Electronic Bus (CEBus) is reviewed. The CEBus network node architecture application layer, network layer, data link layer, physical layer, and access protocol are discussed. The different media used for CEBus communication are described     

Military messaging in IP networks using HF links

In the migration toward network-centric warfare, the NATO STANAG 4406 for Military Message Handling Systems (MMHS) may be used for direct information exchange between high-data-rate strategic users and low-data-rate tactical users by utilizing its new tactical protocol profile. In this article the protocol profiles are tested across a "worst case" tactical HF link providing IP services. There are considerable throughput gains available using the tactical profile. Among the various automated HF technologies tested, the new HDL+ data link protocol, suggested for standardization within NATO, shows the best throughput capabilities for short to medium-size messages on typical HF channels. 3G HF is the most robust technology at low signal-to-noise ratios. The 2G HF throughput performance suffers from inefficient linking procedures. There are optimization issues at different levels of the protocol stack, and implementation choices have great impact on overall performance.     

Application-layer multicasting with Delaunay triangulation overlays

Application-layer multicast supports group applications without the need for a network-layer multicast protocol. Here, applications arrange themselves in a logical overlay network and transfer data within the overlay. We present an application-layer multicast solution that uses a Delaunay triangulation as an overlay network topology. An advantage of using a Delaunay triangulation is that it allows each application to locally derive next-hop routing information without requiring a routing protocol in the overlay. A disadvantage of using a Delaunay triangulation is that the mapping of the overlay to the network topology at the network and data link layer may be suboptimal. We present a protocol, called Delaunay triangulation (DT protocol), which constructs Delaunay triangulation overlay networks. We present measurement experiments of the DT protocol for overlay networks with up to 10 000 members, that are running on a local PC cluster with 100 Linux PCs. The results show that the protocol stabilizes quickly, e.g., an overlay network with 10 000 nodes can be built in just over 30 s. The traffic measurements indicate that the average overhead of a node is only a few kilobits per second if the overlay network is in a steady state. Results of throughput experiments of multicast transmissions (using TCP unicast connections between neighbors in the overlay network) show an achievable throughput of approximately 15 Mb/s in an overlay with 100 nodes and 2 Mb/s in an overlay with 1000 nodes.