CECS 474 - Homework 2
1. Problem Set (Chapter 2)
Problem 1: Consider a short, 10-meter link, over which a sender can transmit at a rate of 150 bits/sec in both directions.
Suppose that packets containing data are 100,000 bits long, and packets containing only control (e.g., ACK or
handshaking) are 200 bits long. Assume that N parallel connections each get 1/N of the link bandwidth. Now consider the
HTTP protocol, and suppose that each downloaded object is 100 Kbits long, and that the initial downloaded object contains
10 referenced objects from the same sender. Would parallel downloads via parallel instances of non-persistent HTTP make
sense in this case? Now consider persistent HTTP. Do you expect significant gains over the non-persistent case? Justify
and explain your answer.
Problem 2: Consider distributing a file of F=15 Gbits to N peers. The server has an upload rate of us=30 Mbps, and each
peer has a download rate of di=2 Mbps and an upload rate of u. For N=10, 100, and 1,000 and u=300 Kbps, 700 Kbps,
and 2 Mbps, prepare a chart giving the minimum distribution time for each of the combinations of N and u for both clientserver distribution and P2P distribution.
2. Solution Submission and Deadline
You only need to submit the solutions to problems 1 and 2 (which are marked through red text color) to BeachBoard.
Submission Deadline: March 7, 2022, 11:00 pm
