This is really news to me. Managed Chromebooks, when possible, use P2P connections to update Chrome OS faster. That is, to save bandwidth and speed up the process, Chromebooks can share the downloaded updates through the local network.
Excerpts from the official documentation:
Beginning with Chrome devices on Chrome version 40 or later, when possible, Chrome devices will use a peer-to-peer (P2P) auto-update behavior that allows faster update of Chrome devices from nearby devices instead of downloading the update from Google’s servers or an intermediate caching proxy, if you have one set up. If peer-to-peer auto-updating fails or is not possible on your network, devices will update through normal channels.
Looks like this is the default set up for managed Chromebooks. If for some reason the Peer to Peer update fails, Chromebooks will go through the normal update method.
The average full Chrome OS software update is 400 MB and minor updates are approximately 50 MB. If you have lots of Chromebooks and Chromeboxes to update, peer to peer makes sense. It will save some bandwidth and lots of time.
Enable P2P Update in a Non-managed Chromebooks
You can enable this feature on a non-managed Chromebook too. If you have more than one Chromebook at your home, this method can speed up the Chrome OS update.
To do this, open Chrome OS shell (Ctrl + Alt + T) and type p2p_update enable. You can replace enable with disable in the same command to disable P2P update.
Chrome OS P2P Updates, the Chrome App
Now meet the Chrome OS app that will show you status of P2p update transfer in your network. Chrome OS P2P Updates, developed by François Beaufort will give you you a detailed view of all Chrome OS P2P Cached Updates available in your local network. Useful if you are managing a fleet of Chromebooks for your company or school.
via François Beaufort.