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Comment by jewel | Hacker News Reader

When Fi was announced they mentioned that public wifi traffic would go through a VPN to google's datacenters. At the time I assumed that they'd just run ALL traffic through the VPN, since that'd make for some very seamless switching. As bad as that would be from a privacy perspective, I trust Google more than T-Mobile or Sprint.

By running everything through the VPN, you'd be able to have TCP connections that didn't break when the network switched, since your device's public IP address would be in a datacenter somewhere.

Also with a VPN you'd be able to send voice traffic over both a carrier connection and the wifi connection at the same time to avoid dropouts.

There is something similar called Multi-path TCP (MPTCP) which uses latency to decide which TCP path to send traffic over.

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> Also with a VPN you'd be able to send voice traffic over both a carrier connection and the wifi connection at the same time to avoid dropouts.

Does this double the bandwidth you're using when MPTCP is in effect?

It would obviously send the data out twice; but once would be over the cell network and the other time over WiFi. Doing so would also help with the far more common Cell<>WiFi transition cases. However as the phone still only has once Cell radio set it would not help with transition between communication bands or carriers.

Since the accounting that actually matters (to Google) is at the data center and based on the way that peering agreements work, I suspect Google would actually find /incoming/ data to be either unimportant or even a benefit to their overall cost operations based on bringing their usage closer to equal. The consumer would only normally care about the cell min used; unless their local ISPs have zero competition (see 90%+ of America).

Precisely - that stable IP between networks is what you need to have completely seamless switches.

This is what Touch Mobile (www.touch.com) does for their handover, for instance.

It should be noted that the VPN only turns on when it automatically connects to pre-approved APs. Google didn't disclose to me what those APs are.

It's not pre-approved APs as far as I'm aware, it's any public AP that has no password or landing page, and isn't manually set by you. If you have wifi assistant enabled, it will automatically try to connect to anything that's open from what I've seen.

That's not what Google Fi support told me:

> Thank you for contacting Project Fi Support! My name is Sydney and I will be glad to assist with your issue regarding WiFi services today. First, your phone should connect automatically to open WiFi networks. They have to be Google verified networks to automatically connect. Here is an article regarding our feature known as WiFi assistant and how it works.

And I did try connecting to an open wifi - no VPN automatically activated (but that isn't the only thing that doesn't work...).

The assistant has to make the connection, not the user. I've seen it work against quite a few different APs including some obscure ones, so I'm not sure there's a list or not. The online docs suggest that it does some performance testing before connecting.

By Google "verified", they seem to mean that the phone runs some tests on the network before actually connecting to the VPN, and disconnecting completely if the Wifi isn't up to par. It would be nice for them to confirm exactly how it works, though.

The VPN only works with access points that the phone automatically connects to through wifi assistant (this excludes any you have manually selected at any point in time). The VPN only works when the phone itself finds a hotspot that you have never selected and decides to connect.

"from a privacy perspective, I trust Google more than T-Mobile or Sprint"

From a privacy perspective, I would not trust an advertising company (Google) more than a telecom. Google is perhaps better about disclosure to a Government entity, but they would be worse about exploiting your data for their own ends.

Seems many here do trust Google with their personal data. So, I suppose that implies they are not only a marketing company, but a good one :)

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