On Thu, Mar 30, 2023, at 15:57, Marcin Nawrocki wrote: > Unfortunately, I ran out of time before presenting the third challenge: > An Initial containing both, the ACK and ServerHello, can skew the RTT > estimation of the client for some deployments (e.g., CDNs). This is > because the QUIC server can be separate from the process that has > access to TLS material, so there is a noticeable delay for fetching the > required TLS data.
Yes, this will affect RTT estimates, but the effect will wash out over time. The net effect is an inflated RTT estimate. You can maybe correct for this using ACK Delay. > Opinions on how to deal with this? Some CDNs split the Initial ACK and > Initial ServerHello into two packets, leading to more padding bytes. > Please see my slides 15-21 [1] for more information. I believe that some people already do this split, yes. I would prefer that servers use subcerts for this: https://datatracker.ietf.org/doc/html/draft-ietf-tls-subcerts
