I agree.

Here's a slightly different example. The common tier for ISP A may have
provisioned bandwidth of 12 Mbps, and 10 Mbps for ISP B. Assuming that
an application doesn't need 11 Mbps, it may make more sense for the app
to pick an ISP A client 12 times out of 22 (55%), and an ISP B client 10
times out of 22 (45%), rather than an ISP A client 100% of the time.

-- Rich

-----Original Message-----
From: Sebastian Kiesel [mailto:[email protected]] 
Sent: Thursday, March 18, 2010 5:42 PM
To: Woundy, Richard
Cc: [email protected]
Subject: Re: [alto] Comments on provisioned bandwidth and ALTO

Hi,

a technical concern regarding the provisioned bandwidth attribute:

If a P2P app uses this information for a peer selection strategy like
"try the highest bandwidth tier peers first" or "try the highest
bandwidth tier peers with higher probability", and if there is a swarm
with many peers but very few of them are in the highest bandwidth tier,
the user experience of these premium customers might be worse than for a
customer with lower provisioned bandwidth (even if the P2P app uses flow
control and congestion control, the initial syn packets alone could
overwhelm the premium customer's links).

So we should be very clear what we want to do with this kind of
information in the application.


Thinking about this for a while, this problem is not limited to the
provisioned bandwidth.  Maybe we need to distinguish between rating
criteria that are commutative (i.e., peer B would be a "good" neighbor
for peer A according to that criterion implies that A would be a "good"
neighbor for B) and those criteria that are not.  Using non-commutative
rating criteria might be risky.

-- Sebastian
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