上海应用技术学院 Computer Networks 期中试卷

上海应用技术学院2013—2014学年第一学期 《计算机网络原理 Computer Networks》期（中） 课程代码: B204212 学分: 3 考试时间: 100 分钟 课程序号: 班级： 学号： 姓名: 我已阅读了有关的考试规定和纪律要求，愿意在考试中遵守《考场规则》，如有违反将愿接受相应的处理。 试卷共 6 页，请先查看试卷有无缺页，然后答题。 I. Abbreviations: (10 points in total) The (everyday English) expansions of the following abbreviations are wanted: A1-10.(1 point each, 10 points in total) A1. OSI A2. MAC A3. CDMA A4. VLAN A5. PPP A6. WAN A7. CRC A8. FDM A9. AP A10. CSMA / CD II. Concepts: (30 points in total) Give the definition or description of the following concepts or names: B1-5 (6 points each, 30 points in total) B1. Which of the OSI layers and TCP/IP layers handles of dividing the transmitted bit stream into frames? The unit exchanged at the network layer is called a packet. Do frames encapsulate packets or do packets encapsulate frames? B2. Please list 3 basic types of network topology. B3. What is the meaning of “propagation delay”? And what is the meaning of “transmission delay”? B4. A bit string, 0111101111101111110, needs to be transmitted at the data link layer. What is the string actually transmitted after bit stuffing? Mark out your stuffing bits by underline. B5. Why we need the MAC sublayer? List three MAC protocols. III. Computation: (40 points in total) The process/procedure or explanation of computation and the correct results are all wanted. C1-5. (8 points each, 40 points in total). C1. What signal-to-noise ratio is needed to put a T1 carrier on a 50-kHz line? The T1 data rate is 1.544Mbps. C2. A 8-bit messages with binary value 0101110 is to be encoded using an odd-parity Hamming code. Compute the code word. Note that odd-parity is used. C3. Frames of 1000 bits are sent over a 1-Mbps channel whose propagation time is 15 msec. Acknowledgements are always piggybacked onto data frames. The headers are very short. Three-bit sequence numbers are used. What is the maximum achievable channel utilization for(a) Stop-and-wait protocol?(b) Sliding window protocol? C4. A 1-km-long, 10-Mbps CSMA/CD LAN (not 802.3) has a propagation speed of 200 m/μsec. Repeaters are not allowed in this system. Data frames are 256 bits long. The first bit slot after a successful transmission is reserved for the receiver to capture the ch