Subject: [Fwd: TCP/IP source models]

From: Carlo Matarasso <[email-masked]>
Date: Fri, 04 Sep 1998 11:12:08 +0200

Subject: Re: TCP/IP source models
From: Chuck Fraleigh <[email-masked]>
To: [email-masked] (Carlo Matarasso)
Cc: [email-masked] (Charles Joseph Fraleigh)
Date: Thu, 3 Sep 1998 10:49:14 -0700 (PDT)

> Sorry in advance for receiving duplicate copies of this message
> 
> I' m looking for mathematical models for TCP/IP sources, for every
> possible service (e.g. WWW, e-mail  ....).
> The thing, that would more help me, were generated (and received)
> traffic patterns of a single TCP/IP source.
> 
> Please send to me, through private mails, any references or results you
> can share.

Dr. Matarasso -

I am currently starting some research into accurate models for TCP
sources. I have not reached any conclusions yet, but I can give you 
a list of some papers I have looked at so far.

1.) Walter Willinger, et. al., "Self-Similarity Through High-Variablility:
Statistical Analysis of Ethernet LAN Traffic at the Source Level," 
Proceedings of ACM SIGCOMM '95, pp. 100-113.

This papers starts with observations of aggregate network traffic and
explains how the self-similar properties of the aggregate traffic can
be attributed to individual ON/OFF sources which exhibit the Noah Effect.
It does not differentiate between WWW, email, or other types of sources.

2.) Vern Paxson and Sally Floyd, "Wide-Area Traffic, The Failure of
Poission Modeling," IEEE/ACM Trans. Networking, June 1995, pp. 226-244.

This paper looks at how individual telnet and ftp sources may be modeled.
It reaches similar conclusions as to the self-similar nature of aggregate
traffic and the large variance of burst sizes for individual source.

The telnet and ftp models have been integrated into a publicly available
network simulator called ns. There is more information on the simulator
at http://www-mash.cs.berkeley.edu/ns/

I do not yet have a good reference for WWW traffic models.

As I mentioned above, I started this research only a few weeks ago, so
I do not have a complete understanding of all of the problems relating
to modeling TCP sources. I would be interested in any additional information 
you might have about this problem.

One final note: You mentioned using generated traces for TCP traffic. There
is a problem with using statically generated TCP traffic because TCP uses
a dynamic flow control mechanism. To accurately model TCP, it is necessary 
to consider how the interaction of multiple flows will affect the flow
control mechanism. You cannot simply take multiple traces of TCP traffic
and combine them.

chuck 

--------------------------------------------------------------------
Chuck Fraleigh                |             [email-masked]
Multimedia Networking Group   | http://www-leland.stanford.edu/~cjf
Stanford University           |