With millions of users downloading the recent Apple iOS update (~800MB - several versions exist, according to the Apple device), it would have been interesting to see the impact on ISP network and outgoing links.
Sonic.net, an ISP from California, US (36,000 subscribers), shared its traffic loads, showing a nice spike on the "D Day" (October 12).
Nevertheless, the impact on it outgoing link was probably low, as according to the ISP's blog post - ".. there is a substantial increase in traffic starting the day the update was released. We host the Apple update content locally on Akamai CDN servers in our datacenter, so this doesn’t affect our network edge, but you can see the bump in traffic from the CDN cluster itself here."
See "The Apple effect on ISP traffic" - here.