The 4 - layer printed circuit board , which proposes good electro magnetic compatibility , electrical trait and heat elimination ; . full / half duplex auto - negotiation support ; diagnostic monitoring for malfunction indication and troubleshooting ; . supporting hot - pluggable ; good compatibility ; good at heat elimination . 1 . 25gbit / s sfp optic transceiver has been deployed in various broadband applications will be used in backbone networks of ring or daisy - chain topologies 我们设计的光纤收发器有良好的电磁兼容性，并保证了电路板的供电特性和散热特性、支持全半双工自适应、具有数据诊断功能、准确方便的判断网络故障、支持热插拔操作、兼容性良好。
The paper not only used the sequence diagrams to descript the cooperation of pda and server in communications , but only adopt petri net , a kind of fdt , to built four different models on protocol ' s dynamic actions . we proposed the constrict expressions : 1 . finding out and fixing the errors , we validated the protocol with petri net theories 在通用的时序图描述通信协议动态交互的基础上，用一种形式化描述技术? ? petri网抽象通信协议的动态行为规范为一种链路层半双工停止-等待协议，从简单到复杂建立4个不同侧重点的petri网模型，分别描述通信协议的不同动态行为：交互，超时，出错处理。
For the last several decades , communications has existed in three separate universes : voice has gone over reserved end - to - end circuits through telco - switches , data has been delivered in packets over equipment maintained by is staff and video has moved over the ether or half - duplex cable 过去几十年中，通信存在于三个独立的领域：话音通过电话公司交换机在预留的端至端电路上传递，数据以包方式在由信息系统工作人员维护的设备上传输，而视频图像在以太或半双工电缆上传送。
Ist - 100m - s / m consists of a module and a hull . the technological characteristics of the former are : 4 - layer printed circuit board , which proposes good electro magnetic compatibility , electrical trait and heat elimination ; full / half duplex auto - negotiation support ; with status leds for malfunction indication and troubleshooting ; supporting insert & pull when electrified ; good compatibility 收发器模块部分的技术特点是：采用四层板，有良好的电磁兼容性，并保证了电路板的供电特性和散热特性；支持全半双工自适应；设有状态指示灯，准确方便的判断网络故障；支持热插拔操作；兼容性良好。
The paper is originated from the project " high - performance ethernet switch research and development " . it investigates a switched ethernet and gives a design and realization of mainboard of a ethernet switch . based on the thorough understanding of principle of ethernet switch , most effort is focused on new technologies emerged at present , such as vlan , multicasting , priority strategy and flow control 本文在讨论以太网交换原理的基础上，主要讨论了交换式以太网出现的新技术：虚拟局域网( vlan ) 、组播、优先级技术、以及半双工和全双工流量控制技术，并设计和实现了24口的10 / 100mbps自协商的交换网板。
Their transmissions are rarely simultaneous , but mainly paroxysmal . second , network that based on this solution is convenient to be upgraded to full duplex . this nic uses dp83820 , which is developed by national semiconductor of american , as the network control chip and could support both half duplex and full duplex just only to modify the software 第二、采用该方案的网络很容易向全双工交换式的网络升级，该网卡采用美国国家半导体( nationalsemiconductor )公司的dp83820作为网络控制芯片，可以同时支持半双工与全双工操作，只需改动软件。
It use a psc to replace the switch , and implement the csma / cd in the network interface card ( nic ) . when the throughput grows and transfer speed is raised , csma / cd will lower the network ' s performance , but think about such truths below , the half - duplex gigabit optic ethernet will have some market space . first , there still exist large amount of small - size local network nowadays ; but they require high transmit speed , such as studio , lab etc , especially multimedia , graph and image processing , virtual reality and advertising 但是，在目前情况下，出于以下几个方面的考虑，使用csma cd方式的半双工千兆位网络也有它的发展空间：第一、在目前的情况下，有大量的小型局域网存在；但是又要求高的传输速率，如工作室、实验室等工作组级的网络，尤其是现在十分常见的多媒体应用、图形图像处理、虚拟现实与广告渲染等方面。
