I have seen my wife's Windows 10 computer upload crap from time to time and I suspected but could not confirm that it is this. How is this even possible, given that we're behind a NAT? TCP simultaneous open, I suppose?
I've not yet been able to figure out how to block these shenanigans. I really don't appreciate MS/Akamai profiting off of my (rather limited) upload bandwidth.
http://arstechnica.com/business/2012/05/skype-replaces-p2p-s...
https://en.wikipedia.org/wiki/Microsoft_Notification_Protoco...
They also introduced serious security problems when they made that change... So instead of Skype messages going from one client directly to another they go through Microsoft's servers (where they are stored and intercepted by TLAs) unencrypted.
They also introduced a new "feature" whereby their systems read everything you write:
http://www.h-online.com/security/news/item/Skype-with-care-M...
If you have a decent router (I have a Mikrotik; DD-WRT or such should work too) you can bucket all Akamai traffic into a low-priority queue. I posted an IP list elsewhere in this story.
It still has some issues when multiple machines download the same update, maybe this is when you home sysadmins could start running a caching server?