Re: iOS 7 update traffic

[Joe Abley <jabley () hopcount ca>]

On 2013-09-23, at 09:41, Glen Kent <glen.kent () gmail com> wrote:

> BTW Linux distributions are available to download via bittorrent, so we
> dont really need Akamai/Limelight here. Is there a reason why Apple has not
> adopted bit-torrent for distribution? Are there legal/commercial
> implications using bit-torrent?

There are upstream congestion issues frequently associated with bittorrent. If you compare

(a) five thousand students on a campus wifi network trying to download a 1GB image from a nearby Akamai cache, and

(b) five thousand students on a campus wifi network seeding a 1GB image to people all over the world

it's not obvious that more pain results from (a) than (b).

Even given the ability of Apple to control the behaviour of the bittorrent agent (which presumably would be built into 
iOS) the impact of such a strategy on an event of this size seems very hard to predict, given a narrow time base and an 
unknowable number of local network constraints.

It doesn't seem impossible to try and optimise the fan-out by giving network operators hooks to influence peer 
selection based on local topology. But it also doesn't sound like an easy general problem to solve (or a problem that 
anybody necessarily wants to spend money on if the relief is only going to be felt once per year on major iOS updates).

(Remember as well that the scale here is very different. With iOS, Apple is the major Unix vendor on the planet by some 
margin. No other single Linux or other Unix/Unix-like distribution comes close, and I am guessing no single operating 
system triggers the update enthusiasm observed with iOS.)


Joe