By utilizing the busy tones to realize the multicast reliability , rmac has three novelties : it uses a variable - length control frame to stipulate an order for the receivers to respond , thus solving the feedback collision problem ; it extends the usage of busy tone for preventing data frame collisions into the multicast scenario ; and it introduces a new usage of busy tone for acknowledging data frames positively 例如, ieee 802 . 11 ,现今应用最广泛的无线mac协议,仅在单播unicast通信方式下提供可靠数据传输服务,而对于组播和广播两种通信方式,它仅传输数据一次,即使数据传输出错,也不会重传。然而近几年来,由于无线网络应用的蓬勃发展,人们逐渐认识到在mac层提供可靠组播服务是非常必要的。
It is composed of three mian protocols : call synchronization protocol , control frame transmission protocol based on arq mechanism and data transmisstion protocol based on slot precontract mechanism . one scan channel table is shared in the hfmanet . the nodes in the same dwell group work in the same scan channel , and the nodes in the different dwell group work in the different scan channel 该协议的网络拓扑结构采用分布式分群结构,协议不同于传统的短波点到点及需要中心节点转发的组网方式,而是初步实现了短波电台之间多跳组网功能,其协议内容主要包括同步呼叫协议、基于arq的控制帧传输协议和基于虚电路及时隙预约方式的数据帧传输协议。
In the first part of this thesis , current situation of the access network and the technical of pon are introduced briefly . then , the epon system structure , osi protocol model , especially the mpcp sublayer are introduced , the epon control frame and data frame changed form ethernet frame are analyzed 本文首先介绍接入网技术的发展状况和无源光网络的主要技术类型,以及epon系统的网络结构、 osi分层模型,重点介绍epon系统特有的mpcp子层,分析epon系统对以太网数据帧所做的修改和新添加的epon控制帧。
With the further promotion in our country of wto , the market of our country is pouring into constantly foreign large - scale enterprise and products , the tobacco trade ca n ' t escape by luck outside the globalization competition pattern either ; world health organization ( who ) through " tobacco control frame convention " 2003 , raise new rounds of momentum high against the cigarette tide in the whole world , make the tobacco living environment receive more harsh restriction 随着wto在我国的进一步深化,国外大型企业和产品不断涌入我国市场,烟草行业也不能幸免于全球化竞争格局之外; 2003年世界卫生组织( who )通过了《烟草控制框架公约》 ,在全球掀起了新一轮声势更高的反烟浪潮,使烟草生存环境受到更为苛刻的限制。
This text has analysed load balancing method of existent especially lvs cluster system and recommended the net packet and netfilter ’ s frame structures in the linux operating system ; it has compared the cooperative - type - cluster with tradictional cluster in the net packets ’ queue ways and with active cluster in the load balancing dispatcher way , which has reflected the superiority of cooperation type cluster ; the three major parts of the cooperative - type - cluster have been designed and realized in this text , which includes sync packets ’ priority service for dmcs 、 “ priority and avoid sudden load unbalance ” dispatch way at the cooperation of nodal servers and director and active nodal server which ensure cluster normally running when cluster join or rduce node server ; the cooperative - type - cluster ’ s control frame controlled by homepage has been constructed ; the mulit - services cluster system has been realized ; this text has used the existing server pressure testing tools to test the cooperative - type - cluster and lvs cluster , then has comparaed and analysed the two 本文分析了现有服务器集群特别是lvs集群系统的负载均衡方法,介绍了linux系统下的报文和netfilter的框架结构;将所提出的合作式集群与传统集群在报文排队方式上进行比较,与主动式集群在负载均衡调度方式上进行比较,体现了合作式集群的优越性;设计并实现了合作式集群体系结构的三大部分:针对分布式测控系统的加权服务、负载均衡器与节点服务器合作式“加权防突”负载调度、保证集群运行不受加减节点干扰的主动性真实服务器;构建了通过网页界面控制合作式集群的控制框架;实现了一个可运行的合作式多服务集群系统,运用现有服务器压力测试工具对合作式集群和lvs集群进行负载测试,并对测试结果进行比较分析,同时通过压力测试实现加权服务。