Date: Sun, 19 Jan 2020 23:17:56 -0800
From: Christian Huitema <notifications@github.com>
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Message-ID: <quicwg/base-drafts/issues/3333/576138925@github.com>
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Subject: Re: [quicwg/base-drafts] Padding outside QUIC packet (#3333)
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I think it is much simpler to say that:

1) For the purpose of verifying that an Initial packet is larger than the required minimum, all bytes count.
2) For all other purposes, including congestion control and amplification control, only valid packets count.

Then it becomes a choice of implementations. Padding with padding frames is not hard, many implementations do it. Implementations that want to save a few lines of code or a few CPU cycles could pad their initial packets otherwise, but they will bear the impact on performance.

Also, consider the coalescing requirement about DCID: "Senders MUST NOT coalesce QUIC packets for different connections into a single UDP datagram. Receivers SHOULD ignore any subsequent packets with a different Destination Connection ID than the first packet in the datagram." That's consistent with "ignore the junk for all purposes except maybe verifying packet size".

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<p>I think it is much simpler to say that:</p>
<ol>
<li>For the purpose of verifying that an Initial packet is larger than the required minimum, all bytes count.</li>
<li>For all other purposes, including congestion control and amplification control, only valid packets count.</li>
</ol>
<p>Then it becomes a choice of implementations. Padding with padding frames is not hard, many implementations do it. Implementations that want to save a few lines of code or a few CPU cycles could pad their initial packets otherwise, but they will bear the impact on performance.</p>
<p>Also, consider the coalescing requirement about DCID: "Senders MUST NOT coalesce QUIC packets for different connections into a single UDP datagram. Receivers SHOULD ignore any subsequent packets with a different Destination Connection ID than the first packet in the datagram." That's consistent with "ignore the junk for all purposes except maybe verifying packet size".</p>

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