iOS 7 update traffic

Blake Dunlap ikiris at
Mon Sep 23 14:31:32 UTC 2013

Bit torrent is a way to lighten the load on the originator, and to increase
the speed of the acquisition from the receivers. It is not a tool to
decrease network load, if anything it does the opposite most of the time.

Every now and then, a client will find a local network peer, but its
usually an accident more than anything from the algorithm it uses to try to
find the fastest senders with pieces it needs. This is most often a product
of far end congestion and what pieces are completed, and rarely upstream
related barring major issues. The algorithim is self greedy, not
altruistic, and definitely not written with ISP load issues in mind.

I'd much prefer CDN content over bittorrent from the ISP side.


On Mon, Sep 23, 2013 at 9:02 AM, Joe Abley <jabley at> wrote:

> On 2013-09-23, at 09:41, Glen Kent <glen.kent at> 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

More information about the NANOG mailing list