Re: [quicwg/base-drafts] max_ack_delay is unknown when a new connection is established (#2638)

Jana Iyengar <> Wed, 24 April 2019 08:33 UTC

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Subject: Re: [quicwg/base-drafts] max_ack_delay is unknown when a new connection is established (#2638)
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@marten-seemann : It's not about the RTT, it's about the PTO, or crypto timeout to be more precise. It's reasonable to continue using max_ack_delay for RTT computations, since it caps ack_delay (ack_delay should be 0 or something very small for those anyways). But when computing the crypto timeout, we don't want to include the max_ack_delay for the reasons you cite.

The draft currently does not have the max_ack_delay being used for the crypto retransmission timer, which was an oversight.  We'll clean that up separately, but fortuitously, this means that there's no max_ack_delay in the pseudo_code or text to change.

I don't mind initializing it to 0 or any value, but it won't have any real effect on endpoint behavior based on the draft.  max_ack_delay doesn't kick in until after the handshake is roughly complete.

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