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Re: [tor-bugs] #6401 [Analysis]: Update Tor network models from CSET paper
#6401: Update Tor network models from CSET paper
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Reporter: robgjansen | Owner: robgjansen
Type: task | Status: new
Priority: normal | Milestone:
Component: Analysis | Version:
Keywords: simulation, performance, network model | Parent:
Points: | Actualpoints:
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Comment(by robgjansen):
After thinking about this, I think we have '''too many web clients'''.
We originally wanted ~95% of our ''connections'' to be web, according to
the now outdated [http://freehaven.net/anonbib/cache/mccoy-pet2008.pdf
shining light paper] from McCoy etal. Since each of our simple clients
only create one connection, we simply configured ~95% of our ''clients''
as web, and moved on.
However, web page downloads usually require many, many GET requests for
all the embedded images and css files, etc - 45-ish on average,
[https://developers.google.com/speed/articles/web-metrics according to
Google]. Google also says that the GETs would be directed to 8 different
hosts, on average. So a single web page would have counted as about 8
separate connections in the Mccoy study.
But each page only counts as a single connection in our model, i.e. each
web client in our simulation actually represents 8 connections and all the
data they download with a single connection. So, the 95% of the clients we
have could be off by a factor of 8, roughly. This might explain why the
load balance is slightly off in our experiments above.
'''So, what do we really want?'''
Ideally, a client that does what we actually want, i.e. a web browser that
downloads embedded objects with several connections in parallel. Thats
item 3 in the ticket description. Since the browser client isn't ready
yet, we'll make due with our simpler single-GET client. The connection
balance might not be right, but hopefully the load will.
We don't just want to cut our web clients by a factor of 8, because each
of our web clients are likely representing several real clients anyway (we
are likely downloading more webpages that a real client would). But, it
seems reasonable to drop them from 2300 down to 1500. This should help
move the load where we actually want it.
Sorry this got long. Not sure if anyone even reads it... but I'd love
comments.
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6401#comment:6>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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