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

On Oct 14, 2008, at 1:07 PM, Ye WANG wrote:

> On Tue, Oct 14, 2008 at 10:55 AM, Nicholas Weaver <nweaver@icsi.berkeley.edu 
> > wrote:
>
> On Oct 14, 2008, at 7:40 AM, Lars Eggert wrote:
>
> FYI, there's at least one more proposal in this space: the Ono stuff  
> from Northwestern (http://www.aqualab.cs.northwestern.edu/projects/Ono.html 
> ). 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.
>
> Basically, this is freeloading on the akamai DNS infrastructure to  
> create a "topology oracle": which nodes are close in terms of  
> network topology as a common proxy for bandwidth.
>
> It doesn't need "ALTO boxes" only because someone else has colleced  
> that information, and that there is a separation between the query  
> replying infrastructure (through DNS) and the measurement  
> infrastructure.
>
> However, it does bring up a good point:  DNS games allow the ability  
> to divorce the measurement infrastructure from the reporting  
> infrastructure, and to create a reporting infrastructure that can  
> always work both with and without ISP cooperation.
>
> This is a very good comment on the architecture on "ALTO box".    
> Just to
> clarify on a risk of building an Internet infrastructure based on a  
> hack of
> using the Akamai DNS infrastructure to create a "topology oracle".
> You may already know it, but some others may not. So I would like to
> point it out.
>
> Akamai DNS redirection considers not only topology, but also  
> Akamai's own
> server state, and Akamai's own redirection policy.  To illustrate  
> this,
> consider a simple example where Akamai temporarily (e.g., during  
> maintenance,
> or misconfiguration, or under attack, or whatever reason) redirects  
> users
> from distant geographic locations to the same set of servers. This  
> may result
> in these users being deemed "close together" when in fact they are  
> not.
>
> This is not limited to Akamai. DNS redirection typically considers not
> only topology, but also the state and policy of whoever controls it.
>

To be fair, I don't think anyone was recommending Ono, merely noting  
it was one that has been proposed and so should be included in the  
list. While a cute systems hack that might make something work better  
today, it's pretty clearly not a good interoperable and long-term  
solution.

Phil
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