计算机英语教程 教学课件 ppt 作者 吕云翔 杨雪 林珣_ Unit 7

1、Unit 7 Computer Network,计算机英语教程 教学课件,Contents,Part 1 Reading and Translating Section A: Ethernet Section B: Wi-Fi Section C: Location-based Service Part 2 Simulated Writing: Instructions Part 3 Listening and Speaking Dialogue: Setting up Wireless Network Listening Comprehension: IPv6the Next Generation Dictation: Router,1.1 Ethernet,Introduction History General Description,1.1 Ethernet,Complex Sentences Original: The combination of the twisted pair versions of Ethernet for connecting end systems

2、 to the network, along with the fiber optic versions for site backbones, is the most widespread wired LAN technology Translation:以太网的用于将终端系统连接到网络的双绞线版本与用于场地主干网的光纤版本的组合，是最为广泛使用的有线局域网技术。,1.1 Ethernet,Complex Sentences Original: These systems replaced the coaxial cable on which early Ethernets were deployed with a system of hubs linked with unshielded twisted pair (UTP), ultimately replacing the CSMA/CD scheme in favor of a switched full duplex system offering higher performance. Translation:这些系统用以

3、非屏蔽双绞线链接的网络集线器系统替代了基于同轴电缆所部署的早期以太网，并最终选择一个能提供更高性能的可交换全双工系统替代了载波侦听多路访问/冲突检测模式。,1.1 Ethernet,Exercises I. Read the following statements carefully, and decide whether they are true (T) or false (F) according to the text. _1The name “Ethernet” was derived from the similar fundamentals between computers communicating over a shared coaxial cable and radio broadcast systems over the ether. _2Ethernet, token ring, FDDI and ARCNET LAN are all LAN standards. _3Data packets are blocks of data that are indi

4、vidually sent and delivered, via which Ethernet stations communicate with each other. _4A specific protocol can be identified via the packet type it uses in current Ethernet. _5Now, most manufacturers build smaller network card with decreasing cost and the reduced panel space in PC,1.1 Ethernet,II. Choose the best answer to each of the following questions. 1Which of the following has been outdated among wired LAN technology? AThe shielded twisted pair BThe fiber optic CThe coaxial cable DThe uns

5、hielded twisted pair,C,1.1 Ethernet,II. Choose the best answer to each of the following questions. 2Which of the following is WRONG about the comparison between the early version and the current version of Ethernet? AThe original address fields in the experimental Ethernet have been changed in the current versions BThe destination and source adresses have been overleapt in the current Ethernet versions CA switched full duplex system can offer higher performance than the CSMA/CD scheme used by th

6、e early Ethernet DThe running speed of the current Ethernet is 100 times and beyond as fast as that of the early versions,D,1.1 Ethernet,II. Choose the best answer to each of the following questions. 3What does the phrase “frame-based” mean appearing at the beginning of the article? AAll generations of Ethernet conform to the multi-layers structure of the OSI reference model BAll generations of Ethernet are built on improving infrastructure from coaxial cable to twisted pair CAll generations of

7、Ethernet base on the same architecture formats and the same interfaces for higher layers DAll generations of Ethernet base on the same physical layer as the underlying frame,B,1.1 Ethernet,III. Translating. 1. Original: Ethernet defines a number of wiring and signaling standards for the physical layer, through means of network access at the Media Access Control (MAC)/Data Link Layer and a common addressing format. Translation: 2. Original Adapters generally come programmed with a globally unique

8、 address, but this can be overridden,either to avoid an address change when an adapter is replaced, or to use locally administered addresses. Translation:,1.2 Wi-Fi,Introduction Uses Advantages and Problems,1.2 Wi-Fi,Complex Sentences 1. Original: In business environments, just like other environments, increasing the number of Wi-Fi access-points provides redundancy, support for fast roaming and increased overall network-capacity by using more channels or by defining smaller cells. Translation:在

9、商业环境中，正如其他环境一样，不断增加的Wi-Fi 访问点数量通过使用更多的信道或定义更小的单元来提供冗余的、对快速漫游的支持以及更大的总网络容量。,1.2 Wi-Fi,Complex Sentences 2. Original: Over the years, Wi-Fi implementations have moved toward “thin” access-points, with more of the network intelligence housed in a centralized network appliance, relegating individual access-points to the role of “dumb” transceivers Translation:经过多年，Wi-Fi 实现已经移向了“瘦”访问点，使用设在一个集中网络装置中的更多网络智能，将单独访问点降级到只是“哑的”无线电收发器的角色。,1.2 Wi-Fi,Exercises I. Read the following statements carefully, and decide whether they are true (T) or false (F) according to the text. _1A Wi-Fi enabled device can connect to the Internet when within range of any wireless network. _2A single Wi-Fi access point has a greater range indoors than outdoors. _3Wi-Fi connections can be disrupted by having other devices in the same area with an interference. _4Wi-Fi in the higher GHz frequency block has better range than in the lower GHz frequency block. _5There are about 80

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