ChomeOS Peer-to-Peer Updates: Looking for insight and impact

[DeeA]

Hey everyone,

We're currently looking into enabling ChromeOS peer-to-peer (P2P) auto update downloads for the devices in our schools. (Workspace Admin > Devices > Chrome > Settings > Device > Auto-update settings > Peer to Peer).  We're trying to understand it better, especially how well it works and what impact it might have on our environment.

If you've turned it on in your environment, how's it going? What are the pros, cons, or unexpected gotchas you've run into?

After digging in the P2P Service Spec, I have a couple of specific areas I'm trying to map out for our district:

1. The Networking Side (mDNS & Ports)

   • mDNS Traffic: Since peer discovery relies on mDNS, and multicast is usually disabled on school Wi-Fi to keep broadcast traffic down, how did you handle this? Did you have to deploy mDNS reflectors to allow discovery across different subnets, or did you keep it strictly local?

   • Ports: For the DNS-SD service (HTTP over port 16725), did you open this up across networks, or are you limiting P2P sharing to devices on the exact same VLAN?

2. Storage Impact

   • Cache Space: The spec mentions cached updates live in /var/cache/p2p. Is ChromeOS always caching these files anyway, or does turning on P2P create a brand-new storage footprint on the device?

   • If it’s net-new, how much storage is it actually eating up on student/staff devices? We’re trying to make sure we don’t accidentally starve user profiles of space.

Would love to hear any lessons learned, configuration tips, or even just a general "yes, it's worth it" or "no, if you're environment has or does not have X or Y, it's not for you."

Thanks!

[zdanenyc]

We have it enabled in my district. It has helped to reduce the burden and strain on our network infrastructure and empowers our devices to update more seamlessly. I personally have not heard concerns about it but clearing up some bandwidth for other educational purposes has been helpful.

[kaned]

My understanding is that the updates are downloaded to a partition and cache automatically.  This can then be enabled to share the update with other devices through mDNS.  Chromebooks use a two copy partition for updating the system which is different than Windows, and I believe it allows for this to work pretty seemlessly.

I do not believe this uses any additional drive space on the users device as this is already downloaded to the device anyway.

We currently have this feature turned off as we were able to get bandwidth to support updates direct from Google, however, we did have this turned on (several years ago now).

Considerations:

• It will consume some serious internal bandwidth when updates are released.  
• Consider any network throttles or bottlenecks (per client bandwidth restrictions, etc).  Any restrictions could affect the end users experience
• If you have Chromebooks across multiple VLANs, you probably don't need to worry about bridging all of those VLANs.  Once a Chromebook in that VLAN grabs an update, they will then distribute it to others.
• If possible, start small, Gauge impact and roll out.
• We typically saw high AP utilization for the first period or two when an update was released, but overall it did seem to work fine.