Re: [p2pi] WG Review: Application-Layer Traffic Optimization (alto)

Karl Auerbach <> Tue, 21 October 2008 20:28 UTC

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Date: Tue, 14 Oct 2008 11:16:43 -0700
From: Karl Auerbach <>
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Subject: Re: [p2pi] WG Review: Application-Layer Traffic Optimization (alto)
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Lars Eggert wrote:

> FYI, there's at least one more proposal in this space: the Ono stuff 
> from Northwestern 
> ( There was a 
> paper at SIGCOMM this year, and their system has the interesting feature 
> that it simply freeloads of Akamai's DNS entries in order to determine 
> who's close to whom. No "ALTO boxes" needed.

Since you mentioned DNS as a proximity tool, I thought I'd go slightly 
awry and point out a bit of work I did a while back that, while not at 
itself at the application level, did try to address some application 
layer optimizations concerns that we had when I was working on binding 
video clients to video services.

The main idea was that neither hop count, asn-path length, ICMP-Echo 
time, DNS answer time, nor TCP-connect-time are very good indicators of 
internet proximity for the purposes of applications that are going to 
make different kinds of demands and need different levels of service. 
And because such proximity questions are likely to be asked frequently, 
the cost of asking the question, and the delay incurred in asking that 
question, ought to be low.

So what I did was to try to blend the notions of potential bandwidth and 
packet size dynamics (from the old integrated services work) with some 
ideas from the old multicast mtrace protocol.  What I came up, and it 
was far, far from complete, was something that needed to live inside the 
router infrastructure, although not on any fast-path part of any router. 
  I called the thing the "Fast Path Characterization Protocol".

(The name may be misleading, the implementation was intended to find a 
path quickly, *not* that it would sit in any router fast-path switching 

So, here it is, 8+ years old:

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