For clarification, Is it soaking up bandwith because its doing the (I forget the term) where it uses your connecion for other Windows 10 users while they update?

"Peer-to-peer transfer" is the term. You mean this hellspawn? https://www.akamai.com/us/en/solutions/products/media-delive...

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.

Ah yes thats the term, I believe (not for downloading) but another MS app Skype uses the same thing when youre talking to someone on a lower bandwith/ADSL connection. I believe it uses the same TCP mechanism of some sort which I havent looked in to.

SuperNodes, which Skype used up until Microsoft bought them out (in May 2011) and stopped doing that (in April 2012)?

http://arstechnica.com/business/2012/05/skype-replaces-p2p-s...

Oh I see. I figured they still used them. Skypes Ui sure has suffered sadly.

It's not just the UI that suffered. The latency and performance of Skype calls dropped significantly after they switched from P2P to Microsoft Notification Protocol 24 (aka MSN Messenger Protocol)...

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...

No I've disabled all of that. It's literally sucking down updates at the maximum capacity of the internet link. Previously the behaviour was to do this, but when the connection was active with other stuff it would throttle the updates back.

This is exactly what I see too. It's because Windows Update opens dozens of connections. Since TCP link-sharing is fair only on a per-connection basis, this means that Windows Update gets the lion's share of the bandwidth.

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.

You can use TCP LEDBAT to keep background downloads fair even with multiple connections. OS X does this for large downloads and software updates, and BitTorrent kinda uses it to not kill your net connection.

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?