计算机网络试卷_2013A含答案.doc

PAGE 1 HUST Examination Answer Sheet Course: Computer Networks (closed-book exam) Jan.2014 Department of Electronics and Information Engineering Solution [Question 1] Network architecture (1) Draw the architecture diagrams of ISO/OSI reference model and TCP/IP network. (2) State the differences between the two architectures. (3) Mark the names of data unit and network equipment in the bottom 4 layers of ISO/OSI diagram. Solution: （1）ISO/OSI reference model TCP/IP model Differences: TCP/IP model is the actual architecture in the Internet, while OSI model is a theoretical architecture. TCP/IP model does not imply strict layering, while OSI model implies strict layering. In TCP/IP model, IP serves as the focal point for the architecture. TCP/IP model allows for arbitrarily many different network technologies , ranging from Ethernet to wireless to single point-to-point links. TCP/IP model emphasize implementations of proposed protocols. (2) Physical : bit, repeater or hub Data link : frame, Ethernet switch or bridge Internet : packet, router Transport : message, gateway [Question 2] Principles of network design Select ONE of the following principles, tell its main ideas and provide an example. (1) Keep it simple and stupid (2) Complex edge and simple core (3) Smart sender and dumb receiver Solution: (1) KISS: Keep It Simple and Stupid It means that you should make things simple in the designing. One example following it : Ethernet (2) Complex edge and simple core It means that the hosts are very complex and have many functions while the nodes are very simple and have few functions. One example following it : The design of router, or the functions of TCP and IP Smart sender and dumb receiver It means that the function of sender is more complex than that of the receiver, which is help to improve the robustness and performance of communication protocol. One example following it: The flow control of TCP protocol [Question 3] Error detection (1) Tell