Re: RPR perf: My thoughts
Shahid
It is not wise to say that simulations don't converge when one
uses self-similar traffic. There is numerous ways of generating
self-similar traffic traces that are usable and result in
repeatable experiments.
Also, what has been shown so far is that TCP/IP traffic when not
facing a hard limited bandwidth requirement exhibits
self-similar behavior.
The starts of individual "sessions" can be explained perfectly
well by Poisson behavior.
What has not been shown is what happens to TCP/IP traffic that
is going through a hard-limited (congested) backbone.
Bora
>>>>> "Shahid" == Shahid Akhtar <sakhtartx@xxxxxxxx> writes:
Shahid> Khaled and Harry, Are we assuming self-similar data
Shahid> traffic for the simulations or some version of
Shahid> Poisson based traffic. Most internet traffic is TCP
Shahid> based which has been proven to be self-similar.
Shahid> The problem with simulating self-similar traffic
Shahid> (since it has infinite variance) is that the
Shahid> simulations do not converge.
Shahid> There are solutions via some analytical methods, but
Shahid> then the performance would be done mostly
Shahid> analytically.
Shahid> Regards,
Shahid> Shahid Akhtar Cyras Systems
Shahid> ----- Original Message ----- From: Harry
Shahid> <mailto:hpeng@xxxxxxxxxxxxxxxxxx> Peng To:
Shahid> khaledamer@xxxxxxx <mailto:khaledamer@xxxxxxx> Cc:
Shahid> Changcheng Huang (E-mail)
Shahid> <mailto:changcheng.huang@xxxxxxxxxxxxxxx> ;
Shahid> Reflector <mailto:stds-802-rprsg@xxxxxxxx> RPRSG
Shahid> (E-mail) Sent: Thursday, January 25, 2001 2:12 PM
Shahid> Subject: RPR perf: My thoughts
Shahid> Khaled: <<Performance Ad Hoc Proposal.ppt>>
Shahid> At last......As promised from last week's meeting.
Shahid> Attached is some charts that capture to what we
Shahid> discussed over lunch. As you can see it addresses
Shahid> Raj's request for cut-through versus store and
Shahid> forward.
Shahid> You are welcome to modified the chart. I'm
Shahid> basically requesting a need for a common test
Shahid> harness. We need sponsors for the harness modules.
Shahid> I've also tried to summarize the different RPR MAC
Shahid> proposals. We can seek each proposal's supporter to
Shahid> do the simulation for each proposal.
Shahid> Follow your guideline on traffic profile and metric
Shahid> we shall have a good platform for comparing the
Shahid> different proposals.
Shahid> I don't see how we can compare the results if we do
Shahid> not set a common simulation framework for each RPR
Shahid> node.
Shahid> Comments.....
Shahid> Regards,
Shahid> Harry
Shahid> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0
Shahid> Transitional//EN"> <HTML><HEAD><TITLE>RPR perf: My
Shahid> thoughts</TITLE>
Shahid> <META content="MSHTML 5.00.2919.6307"
Shahid> name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY
Shahid> bgColor=#d8d0c8> <DIV><FONT face=Arial size=2>Khaled
Shahid> and Harry,</FONT></DIV> <DIV> </DIV> <DIV><FONT
Shahid> face=Arial size=2>Are we assuming self-similar data
Shahid> traffic for the simulations or some version of
Shahid> Poisson based traffic. Most internet traffic is TCP
Shahid> based which has been proven to be
Shahid> self-similar. </FONT></DIV> <DIV> </DIV>
Shahid> <DIV><FONT face=Arial size=2>The problem with
Shahid> simulating self-similar traffic (since it has
Shahid> infinite variance) is that the simulations do not
Shahid> converge. </FONT></DIV> <DIV> </DIV>
Shahid> <DIV><FONT face=Arial size=2>There are solutions via
Shahid> some analytical methods, but then the performance
Shahid> would be done mostly analytically.</FONT></DIV>
Shahid> <DIV> </DIV> <DIV><FONT face=Arial
Shahid> size=2>Regards,</FONT></DIV> <DIV><FONT face=Arial
Shahid> size=2></FONT> </DIV> <DIV><FONT face=Arial
Shahid> size=2>Shahid Akhtar</FONT></DIV> <DIV><FONT
Shahid> face=Arial size=2>Cyras Systems</FONT></DIV>
Shahid> <BLOCKQUOTE style="BORDER-LEFT: #000000 2px solid;
Shahid> MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT:
Shahid> 5px; PADDING-RIGHT: 0px"> <DIV style="FONT: 10pt
Shahid> arial">----- Original Message ----- </DIV> <DIV
Shahid> style="BACKGROUND: #e4e4e4; FONT: 10pt arial;
Shahid> font-color: black"><B>From:</B> <A
Shahid> href="mailto:hpeng@xxxxxxxxxxxxxxxxxx"
Shahid> title=hpeng@xxxxxxxxxxxxxxxxxx>Harry Peng</A> </DIV>
Shahid> <DIV style="FONT: 10pt arial"><B>To:</B> <A
Shahid> href="mailto:khaledamer@xxxxxxx"
Shahid> title=khaledamer@xxxxxxx>khaledamer@xxxxxxx</A>
Shahid> </DIV> <DIV style="FONT: 10pt arial"><B>Cc:</B> <A
Shahid> href="mailto:changcheng.huang@xxxxxxxxxxxxxxx"
Shahid> title=changcheng.huang@xxxxxxxxxxxxxxx>Changcheng
Shahid> Huang (E-mail)</A> ; <A
Shahid> href="mailto:stds-802-rprsg@xxxxxxxx"
Shahid> title=stds-802-rprsg@xxxxxxxx>Reflector RPRSG
Shahid> (E-mail)</A> </DIV> <DIV style="FONT: 10pt
Shahid> arial"><B>Sent:</B> Thursday, January 25, 2001 2:12
Shahid> PM</DIV> <DIV style="FONT: 10pt
Shahid> arial"><B>Subject:</B> RPR perf: My thoughts</DIV>
Shahid> <DIV><BR></DIV> <P><FONT face=Arial
Shahid> size=2>Khaled:</FONT> <BR><FONT color=#000000
Shahid> face=Arial size=2><<Performance Ad Hoc
Shahid> Proposal.ppt>> </FONT></P> <P><FONT face=Arial
Shahid> size=2>At last......As promised from last week's
Shahid> meeting.</FONT> </P> <P><FONT face=Arial
Shahid> size=2>Attached is some charts that capture to what
Shahid> we discussed over lunch.</FONT> <BR><FONT face=Arial
Shahid> size=2>As you can see it addresses Raj's request for
Shahid> cut-through versus store and forward.</FONT> </P>
Shahid> <P><FONT face=Arial size=2>You are welcome to
Shahid> modified the chart. </FONT><BR><FONT face=Arial
Shahid> size=2>I'm basically requesting a need for a common
Shahid> test harness.</FONT> <BR><FONT face=Arial size=2>We
Shahid> need sponsors for the harness modules.</FONT> </P>
Shahid> <P><FONT face=Arial size=2>I've also tried to
Shahid> summarize the different RPR MAC proposals.</FONT>
Shahid> <BR><FONT face=Arial size=2>We can seek each
Shahid> proposal's supporter to do the simulation for each
Shahid> proposal.</FONT> </P> <P><FONT face=Arial
Shahid> size=2>Follow your guideline on traffic profile and
Shahid> metric we shall have a good platform for comparing
Shahid> the</FONT> <BR><FONT face=Arial size=2>different
Shahid> proposals.</FONT> </P> <P><FONT face=Arial size=2>I
Shahid> don't see how we can compare the results if we do
Shahid> not set a common simulation framework</FONT>
Shahid> <BR><FONT face=Arial size=2>for each RPR
Shahid> node. </FONT></P> <P><FONT face=Arial
Shahid> size=2>Comments.....</FONT> </P><BR> <P><FONT
Shahid> face=Arial size=2>Regards,</FONT> </P> <P><FONT
Shahid> face=Arial size=2>Harry
Shahid> </FONT></P></BLOCKQUOTE></BODY></HTML>