S-38.3183 Exercise 4: analysing active measurements
	 ***************************************************
			     Spring 2007
		Markus Peuhkuri <puhuri@netlab.tkk.fi>

This fourth exercise gives you a iperf UDP packet traces.  Traces were
generated in testing multicast traffic.  Traces are in two pairs:

* multicast group 1: host-1 and host-2

* multicast group 2: host-3 and host-4

Clocks were somewhat syncronised (i.e. free-running clocks that had
been syncronised with NTP at some point of time) thus there may be a
significant clock offset and skew.

Each packet was time-stamped by sender when it was sent and then at
received when it was received.  Each packet also included sequence
number.  Test time was approximately 10 minutes.

Trace file format
=================

Each file (host-N.dat) has following tab-delimeted format:

1. packet id (start from 0 and is incremented by one for each packet)
2. packet length (includes IP and UDP headers)
3. seconds since measurement epoch when packet was received
4. seconds since measurement epoch when packet was sent
5. (don't care)

Traces can be found in gzip-compressed format from
http://www.netlab.tkk.fi/opetus/s383183/k07/exercises/iperf/ 

Task
====

Each students selects a set of trace files based on one's student id.
If student id is even, then one uses host-1 and host-2, if odd, then
host-3 and host-4.

Based on trace files you should answer following:

1. What was average bit rate at sender and each receiver

2. How many packets were lost

3. How long were silent periods (max 5 longest)

4. Excluding long silent periods (>1.5 s), what was packet loss rate

5. What you can say about packet delay, clock error and skew?  If
   possible, try to give some bounds for packet delay.

Return of this exercise
=======================

The dead-line for this exercise is April 30th, 2007.  One must submit
results by email to s383183-exercise@netlab.tkk.fi. No returns in
paper format or otherwise are allowed. The reports must be in plain
text or pdf-format and sent as attachments to the email message. Do
not forget your name and study book number from your report.