Date: Fri, 27 Jan 2017 22:28:10 +0100
From: Christian Decker <decker.christian@gmail.com>
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Subject: Re: [bitcoin-dev] Three hardfork-related BIPs
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On Fri, Jan 27, 2017 at 03:47:20PM -0500, Greg Sanders via bitcoin-dev wrote:
> Note that the 4MB number comes from a single network metric.
> 
> Quotes directly from the paper in question:
> http://fc16.ifca.ai/bitcoin/papers/CDE+16.pdf
> 
> >Our results hinge on the key metric of effective throughput in the overlay
> network, which we define here as which blocks propagate within an average
> block interval period the percentage of nodes to.
> ...
> >Note that as we consider only a subset of possible metrics (due to
> difficulty in accurately measuring others), our results on
> reparametrization may be viewed as upper bounds: additional metrics could
> reveal even stricter limits.
> 
> It says nothing about any mining centralization pressure, DoS attacks, etc.
> A single metric among many we have to contend with.
>

As one of the authors of that paper and the source of the measurement
data I'd also like to point out that the 4MB number is indeed intended
as an optimistic upper bound on todays network capacity.

More importantly it's not a black and white situation, where there is
a magic number beyond which Bad Things (TM) happen, it's a spectrum on
which we can see a few threshold beyond which we _know_ Bad Things
definitely happen. Miner centralization pressure is felt earlier.