Re: [quicwg/base-drafts] Add max_bytes_before_ack to transport (#1715)

Christian Huitema <> Wed, 12 September 2018 18:06 UTC

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From: Christian Huitema <>
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Subject: Re: [quicwg/base-drafts] Add max_bytes_before_ack to transport (#1715)
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@ianswett I agree that receivers could hamper senders' performance if they delay ACK too much. We should say that explicitly in the recovery draft. But sending ACKs too frequently also affects the senders' performance, and we should say that too. Bottom line, it is a balance.

We probably want to set default requirements for the number of packets before ACK and for the max ACK delay -- your arbitrary choices of 10 packets and 10 ms look as good as any, or maybe the min of that and 1/4th of the congestion window (for bytes/packets) or the RTT (for ACK delay), with something like at least two packets and 1ms as safe minimum. It would set a reasonable default. Anything else is dependent of the congestion control implementation at the sender, and probably requires cooperation between sender and receiver. That's what extensions are for.

But I do not think that adding this "byte limit" concept is useful, especially if there is no way to change it during the course of the connection.

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