CDA 4527: Computer Communication Networks
Fall 2005
Homework 3
(assigned 11/09; due: 11/16 in class by submitting hardcopy)
1. Chapter 4: What are the three major routing protocols used in Internet? Give their full name and their acronym. Which protocol is mainly based on link-sate algorithm? Which protocol is mainly based on distance vector algorithm?
2. Chapter 4, problem 29. Also answer why the network Y does not know about the existence of network B?
Chapter 5:
3. What MAC protocol does Ethernet use? What MAC protocol does 802.11b wireless LAN use? Why Ethernet has a much higher transmission efficiency than slotted ALOHA? What are the basic differences between Ethernet switch and hub?
4. Two-dimensional parity scheme: Consider the data bit stream 10101 01000 01110 10001 00001. use the 2-dimensional parity code that has 5 rows and 5 columns (use even parity scheme)
a). Write out the parity code in the matrix format as shown in lecture slides Chapter5-part1.ppt (page 10)
b). Suppose the received data bit stream is 10101 01100 01110 10001 00001, which has one bit error. Explain how you use the parity code to detect this bit error.
5. Chapter 5, problem 4 (page 494).
6. Chapter 5, problem 5.
7. Suppose a company has obtained a block of IP space, in the form of 128.119.152.0/11. How many IP addresses have been allocated to this company? Now this company wants to build 4 subnets, each subnet having the same amount of IP addresses, and 4 subnets use up all allocated IP addresses. What are the 4 subnet address space? What is the subnet mask for each subnet?
Chapter 6:
8. What is the working radio frequency and bandwidth of 802.11b, 802.11g, and 802.11a ? Why wireless MAC protocol does not use "collision detection"?
9. Compared with Ethernet MAC protocol, wireless MAC protocol has added DIFS, SIFS, RTS, CTS. Explain their full names, where are they used? Why wireless MAC protocol uses RTS/CTS?
10. Chapter 6, problem 5.
11. Chapter 6, problem 6. Suppose each frame header is 32 bytes, which is the length of RTS, CTS, and ACK frames. The 1,000 bytes data is able to be put into one data frame.