Dear All,
Thank you very much for numerous and quick replies
for my email. I must say that nanog list is really highly responsive.
I needed some time to digest your comments and try
some new ideas. I share the preliminary results with you now, begging for
further comments.
The problem was (and still is) to find a good
heuristic to distinguish between commercial (COM) and educational/research/academic
(EDU) ASes.
*EDU_Abilene*
My first approach (see my original email) was to
extract a list of all destinations announced by Abilene. (The assumption is that Abilene generally does not
announce commercial prefixes.) This results in a list, call it “EDU_Abilene”,
of 1333 ASes.
*EDU_description*
Some of you suggested looking at the names and
descriptions of ASes. I used the AS list available at:
http://www.multicasttech.com/status/asn_expand.txt
and searched the last column
("Organization") for the following strings:
"Universit|Univerz|Universida|research|education|science|scientif|academic|college|institut|laborator|school|ecole|
edu|R&D|library|academy|Etudes"
This approach finds 1796 "educational"
ASes, call this set “EDU_description”.
Of course, these two lists overlap, but less than I
expected. In particular:
len(EDU_Abilene)=1333
len(EDU_description)=1796
union(EDU_Abilene, EDU_description)=2269
intersection(EDU_Abilene, EDU_description)=860
For many reasons, these lists are far from being very
precise. For instance EDU_Abilene contains AS 7132 (AT&T) and AS 8075 (Microsoft).
Therefore I need further data sets or filtering methodology. This raises some
questions:
1) What other EDU networks (preferably with BGP
tables available in the web) can I take as examples of ASes that (generally) do
not announce commercial prefixes? Based on them I could construct lists similar
in spirit to EDU_Abilene. I guess, the more the better.
2) Do you know of other lists, similar to http://www.multicasttech.com/status/asn_expand.txt
? Maybe a longer description or a www related to an AS would help the
method I use to create EDU_description. Do you think the strings I use in my
search are appropriate?
*AS relationships*
Another approach is to exploit the AS relationships. Most
of you agree that usually EDU ASes are not providers for COM customers. This
suggests a way to detect false positives in EDU_Abilene and EDU_description (or
in their union). For every EDU node check how many COM customers it has, i.e., EDU
provider --- COM customer relationship. I used the AS graphs with inferred relationships
provided by CAIDA (http://as-rank.caida.org/data/2006/).
This method works well to find good candidates for false positive, but they
should not be blindly accepted. For instance AS 7132 (AT&T) has the highest
number of COM customers (615) and should obviously belong to COM (it is a
member of EDU_Abilene). In contrast, a big component of the EDU backbone, AS
11537 (Abilene)
has 66 COM customers! In general there are about 50 EDU nodes with more than 10
COM customers each.
3) What other “automatic” or “manual”
approaches would you suggest? Or improvements of the ones just described?
I will appreciate even the briefest comments and
suggestions,
Maciej Kurant
Dear all,
I am a PhD student at EPFL, Switzerland. My recent research
interest is in large scale differences between the commercial and academic parts
of the Internet.
Of course, in order to perform this kind of studies I
need a way to distinguish between these two worlds. I’ve learnt that Abilene does not provide
commercial connectivity. This means that BGP prefixes and AS paths announced by
Abilene BGP routers should lead only to research and academic destinations. I
have extracted (from the BGP tables at
http://abilene.internet2.edu/observatory) a list of all such destinations and
obtained 1333 ASes (for data form July 2006). The number looks reasonable, but
I would like to be sure that I am not making a mistake. Therefore I would be
grateful if you could answer the following questions:
1) Is
this approach to obtain a list of research and academic ISPs correct?
2) Do
you maybe know of such lists compiled before?
3) If
I keep not only the destination ASes, but also all ASes on the AS paths towards
these destination I obtain a list of about 1400 ASes. How should I understand
this? Does it mean that some research and academic destinations are reachable
from Abilene
only by traversing the commercial Internet?
4) Of
course, research and academic ASes are often well connected to the commercial
Internet. My guess is that in most cases their peering relationship is
“customer-provider”, where commercial ASes are providers. Is it
possible that an academic AS is a provider for some commercial ASes? If so,
does it happen often?
Thank you in advance for your comments.
Maciej Kurant
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EPFL IC ISC LCA3
Maciej Kurant
PhD Student
CH-1015 Lausanne,
Switzerland
web site: http://lcawww.epfl.ch/kurant
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