Re: [p2pi] After-BoF charter

[Laird Popkin <[e-mail]>]

On Aug 14, 2008, at 1:24 PM, Enrico Marocco wrote:

> John Leslie wrote:
>>   The speed of convergence to optimal is the critical issue: we want
>> a "better-than-random" initial set of peers to try (and possibly an
>> ordered list to try if they prove unsatisfactory.
>>
>>   I think adding the word "inital" would help:
>> "
>> " information to perform better-than-random initial peer selection.
>
> Yes, that's better.

I strongly agree - this clarifies the relationship between ALTO and  
P2P networks quite nicely.

>>>> Protocols used for peer selection optimization will carry  
>>>> information
>>>> related to the topology and the policies of the querying peer's
>>>> network (i.e. queries on behalf of other peers are not allowed).
>>
>>   We should perhaps be careful about this last prohibition. I'm not
>> sure the obvious mechanism (matching the source IP address of a  
>> query)
>> is wise (though I certainly wouldn't prohibit implementations from
>> trying it).
>>
>>   There are obvious potential benefits from letting particular
>> trackers read an ISP's policies (by prior arrangement, usually). A
>> blanket prohibition of this seems unnecessary.
>
> That's true, but, on the other hand, allowing uncontrolled third-party
> queries would be a privacy nightmare, for both users and ISPs. I've
> personally had a discussion with Stanislav, who said that having peers
> doing the ALTO query and passing the response back to a BitTorrent
> tracker would not be too much of a hassle, so, probably, given the  
> costs
> that controlling third-party queries in a reasonable way would  
> imply, it
> could be wise to just forbid them. However, I would really like to  
> hear
> what other people think about this, especially on the P2P side.

A p2p network can query ALTO information through clients, of course.

If ALTO is used by Trackers to decide which peers to connect, then  
it's a matter of getting the right info to the Tracker.

IMO ALTO should allow the expression of an ISP policy that applies  
more broadly than a single client. For example, if a client can get  
the ALTO guidance that "for all of my customers (defined by an IP  
prefix list), please do p2p transfers with the FTTH users (defined by  
an IP prefix list) before other users.") then the p2p service can  
apply that policy to all peers without them all having to individually  
ask the ALTO server.

If ALTO were limited to telling each client what policy to apply to  
its p2p connections, then every p2p client would have to make an ALTO  
query, then pass the response back to the Tracker to analyze and  
apply. This seems like more work all around, so I hope that we don't  
restrict ALTO to this case.

>>>> It is reasonable to expect that applications will use such  
>>>> protocols
>>>> to discover Autonomous System (AS) numbers and approximate  
>>>> geographic
>>>> location of peers hosting the needed resources,
>>
>>   I don't even _understand_ this.
>>
>>   Current trackers _do_ try to find these pieces of information, but
>> IMHO they're suboptimal substitutes for information ISPs could  
>> provide.
>> I see no reason to include such text in a charter.
>
> Right, we have let them in exactly because that's the kind of
> information a third-party non-ISP ALTO service provider could provide
> (ip2location and "looking glass" web services already do, just in a
> non-standard way). We could get rid of those pieces of information,  
> but
> that would probably reduce the suitability of ALTO for non-ISPs.

The IP to ASN lookup services are proprietary and somewhat inaccurate.  
If ISPs can provide a standard, precise mechanism for determining  
which users are within their network,  that would probably be better.  
Of course, for other ISPs p2p networks would continue to use the  
existing mechanisms, so this isn't a matter of doing something  
impossible, but more a matter of introducing a more precise, efficient  
mechanism to do what is done now.

>
> -- 
> Ciao,
> Enrico
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