Subject: [quicwg/base-drafts] Ttwo paras are quite confusing (#4271)

From: Lars Eggert <[email-masked]>
Date: Wed, 28 Oct 2020 06:54:12 -0700

>  QUIC depends upon a minimum IP packet size of at least 1280 bytes.
  This is the IPv6 minimum size ([IPv6]) and is also supported by most
  modern IPv4 networks.  Assuming the minimum IP header size of 40
  bytes for IPv6 and 20 bytes for IPv4 and a UDP header size of 8
  bytes, this results in a maximum datagram size of 1232 bytes for IPv6
  and 1252 bytes for IPv4.
>
>  The maximum datagram size MUST be at least 1200 bytes.

The previous two paras are quite confusing. I think the first para refers
to the max packet size in the network layer, but the second para is not clear,
nor is the next para.

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From: Martin Thomson <[email-masked]>
Date: Wed, 28 Oct 2020 18:24:49 -0700

The paragraph preceding the first is this:

> The maximum datagram size is defined as the largest size of UDP payload that can be sent across a network path using a single UDP datagram.

So it is clear what the second paragraph means.  QUIC doesn't operate if the network is incapable of carrying a datagram payload of 1200 bytes.  I think that rewording that way might help.

What is less clear is where the extra 32 (or 52) bytes go.  In that we've been very generous in providing for header extensions or UDP extensions.  But I don't see a need to explain that aspect.

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From: Martin Thomson <[email-masked]>
Date: Thu, 29 Oct 2020 16:42:30 -0700

Closed #4271 via #4307.

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