Subject: Re: FW: [Re: [Ieprep] ieprep-requirements-01 - reqs 6-10 - discussion request]

From: "Ayyasamy, Senthilkumar (UMKC-Student)" <[email-masked]>
Date: Sat, 9 Nov 2002 20:13:02 -0600

> I'm not terribly impressed by a lot of the published papers 
> on Internet  measurement -- simply because in many cases the 
> measurement did not use enough  controls to  understand what 
> was really being measured.  
  I don't think, this is the case for measurement works. It is 
more common to simulation works, where topoplogy models doesn't
exactly reflect practical network scenarios. Even if thats the 
case, researchers are not to be blamed. They are forced to
anonymize the traces, which sometimes doesn't contain full 
details. Some of the important Server location problems remains
unsolved due to this factor . But, researchers still use heuristics
to find their way out. I know of works which can exactly tell the
places where akamai have kept their servers.
( One would not have imagined, people can find a topology of a
backbone without the help of the particular ISP..
http://www.cs.washington.edu/research/networking/rocketfuel/interactive/
Reason: BGP data/ whois servers are publicaly available.)

> There is some work by folks  at ICIR  on how hard it 
> really is to measure stuff accurately, for example.

  Your probably referring to vern's talk at NRDM. But, vern's
points were more addressed to sceintific process of measurements.
But, some of those concerns are presently being worked out within
IMRG.

> "three armchair theoreticians."
 Sorry ..But, SIP, RTP and many other things came from a research
lab only. So, it is mostly interdependent.

> Are there other more generic presentations on congestion (or lack of it)
> in real production networks that have been presented at ARIN/NANOG/RIPE
> recently ?  Is there data that CAIDA has that is public enough to be
> useful ?

Studying path properties is difficult for various reasons.. Understanding the
congestion nature( where? when? why? ..) are currenly underway. In a way, I am
also studying some of these path properties/traffic nature..

But, you can get some pointers from 
http://www.icir.org/models/
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From: RJ Atkinson <[email-masked]>
Date: Sun, 10 Nov 2002 08:42:34 -0500

On Saturday, Nov 9, 2002, at 21:13 America/Montreal, Ayyasamy, 
Senthilkumar (UMKC-Student) wrote:

> exactly reflect practical network scenarios.

I would agree that most simulation work is much worse, but it
is the case in much of the published measurement work I've seen.

> Even if thats the case, researchers are not to be blamed.

I disagree on why researchers can't get good measurement.  I think the
main reason is (1) lack of good no-cost attachment points for 
measurement
devices and (2) lack of money to pay for a good attachment point at
an exchange.  There are exceptions of course.  RIPE probably has a good
data set.  I understand that someone else on this list is currently 
looking
at the RIPE data set to see what it shows.

> I know of works which can exactly tell the

A combination of routing traces and traffic analysis could yield that
kind of data pretty quickly, but it is orthogonal to whether the 
measurements
are accurate.

> backbone without the help of the particular ISP..

Many people reverse-engineer their provider's backbone topology 
regularly. :-)
I do it with my provider at my home pretty often. :-)

Ran

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From: Ken Carlberg <[email-masked]>
Date: Mon, 11 Nov 2002 15:19:09 +0000

Ran,

> main reason is (1) lack of good no-cost attachment points for measurement
> looking at the RIPE data set to see what it shows.

the above is valid for many.  a third reason, and one I experience on 
occasion, is non-disclosure agreements.  some researchers can and do 
get really nice material from US and non-US ISPs, but simply can't 
disclose it because the research is kept in-house to the folks that 
funded the effort.

-ken