[Pearg] Measuring latency in IP privacy architectures

[Tommy Pauly <[e-mail]>]

Hello,

I was looking at the slides for one of the PEARG talks for tomorrow, and had some questions about one of the graphs. (I likely won’t be able to attend the meeting due to a conflict, so I thought I’d ask here!).

https://datatracker.ietf.org/meeting/112/materials/slides-112-pearg-state-of-the-art-on-privacy-preserving-techniques-used-at-the-network-layer-00 <https://datatracker.ietf.org/meeting/112/materials/slides-112-pearg-state-of-the-art-on-privacy-preserving-techniques-used-at-the-network-layer-00>

There’s a slide titled “Positioning SoA projects on a map”, with two axes—“attack class” and “latency”. While the “class” is a relatively subjective measurement, the latency metric should be pretty straightforward. I assume that the latency axis goes from lowest-latency on the left, and highest-latency on the right. There weren’t any numbers provided, but I was very surprised to see that both Gnatcatcher and iCloud Private Relay were listed further to the right than TOR! In the case of iCloud Private Relay, which I work on, our overall metrics show that the average page load time for the browser going through the relays is actually faster than going direct for most parts of world. To that end, our effective latency is quite good. Can anyone share insight into what the methodology was behind this graph?

More generally, if we’re discussing latency for IP privacy solutions, it would be good to agree on what methodology is appropriate across very different technologies. IP-tunnelling can end up requiring more round trips for typical workflows (due to DNS and TCP handshakes over the tunnel) than CONNECT-style proxying (which can end up doing DNS+TCP+TLS in one round trip). That changes the experience of latency, in addition to the actual round-trip-time between hops.

Best,
Tommy