On Jun 20, 2013, at 1:39 PM, Niels Bakker <niels=na...@bakker.net> wrote:
> You're mistaken if you think that CDNs have equal number of packets going in
> and out.
I'm aware that neither the quantity nor the size of packets in each direction
are equal. I'm just hard-pressed to think of a reason why this matters, and so
tend to hand-wave about it a bit… To a rough approximation, flows are
balanced. Someone requests something, and an answer follows. Requests tend to
be small, but if someone requests something large, a large answer follows.
Conversely, people also send things, which are followed by small
acknowledgements. Again, this only matters if you place a great deal of
importance both on the notion that size equals fairness, and that fairness is
more important than efficiency. I would argue that neither are true. I'm far
more interested in seeing the cost of Internet service go down, than seeing two
providers saddled with equally high costs in the name of fairness. And costs
go down most quickly when each provider retains the full incentivization of its
own ability to minimize costs. Not when they have to worry about "fairness" in
an arbitrary metric, relative to other providers.
The only occasion I can think of when traffic flows of symmetric volume have an
economic benefit are when a third party is imposing excess rent on circuits,
such that the cost of upgrading capacity is higher than the cost of "traffic
engineering" flows to fill reverse paths. And that's hardly the sort of mental
pretzels I want carriers to be having to worry about, instead of moving bits to
customers.
> I think the point is here that networks are nudging these decisions by making
> certain services suck more than others by way of preferential network access.
I agree completely that that's the problem. But it didn't appear to be what
Benson was talking about.
-Bill
