This preview shows pages 1–2. Sign up to view the full content.
CS/ECE 438: Communication Networks for Computers
Spring 2010
Problem Set 7
Due: start of class, (date).
Congestion Control and Performance Analysis
Assigned reading: Peterson and Davie: Chapter 6. All problems carry equal weight. Please show all your work.
1.
Random Early Detection
Consider a FIFO queue with an RED dropping policy, with MaxP=0.02, MinThreshold=20, MaxThreshold=180.
The current AvgLen=60.
a.
Find the drop probability P(count) for count=1 and count=40.
b.
Calculate the probability that none of the 40 packets are dropped.
c.
What is the probability that none of the 40 packets are dropped when AvgLen=220?
2.
Fair Queuing
In this problem you will simply show the scheduling times for a link using the following version of weighted fair
queuing. Packets are stored in perflow queues and perflow counters track how much data has been sent from each
flow. The counters are zero at time zero, and time zero is the first decision time. At each decision time:
1.
Enter packets arriving at the decision time, if any, into the appropriate queues.
2.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Spring '08
 Luo

Click to edit the document details