Subject: [quicwg/base-drafts] Packet header fields cannot be omitted (#3029)

From: Dmitri Tikhonov <[email-masked]>
Date: Fri, 13 Sep 2019 07:07:06 -0700

At the top of page 66 of the [transport draft](https://tools.ietf.org/html/draft-ietf-quic-transport-23), we read:

```
   Every QUIC packet that is coalesced into a single UDP datagram is
   separate and complete.  Though the values of some fields in the
   packet header might be redundant, no fields are omitted.  The
   receiver of coalesced QUIC packets MUST individually process each
   QUIC packet and separately acknowledge them, as if they were received
   as the payload of different UDP datagrams.  For example, if
   decryption fails (because the keys are not available or any other
   reason), the receiver MAY either discard or buffer the packet for
   later processing and MUST attempt to process the remaining packets.
```

The second sentence seems to imply that a field *could* be omitted.

Does this sentence sound odd to anyone else?

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From: Ryan Hamilton <[email-masked]>
Date: Fri, 13 Sep 2019 07:30:38 -0700

While it is perhaps technically redundant, I think it is actually quite helpful. The first sentence says, "complete" but that might be open to interpretation. The second sentence makes it clear what that means. I like it.

YMMV :)

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From: Dmitri Tikhonov <[email-masked]>
Date: Fri, 13 Sep 2019 07:41:53 -0700

My issue is not with the redundancy of the second senteance, but rather with its meaning.  The specification that "no fields be omitted" implies that fields *could be* omitted -- but they can't be:  There are no optional fields in packet headers.

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From: Nick Banks <[email-masked]>
Date: Fri, 13 Sep 2019 07:47:26 -0700

Maybe change the second sentence to something like:
```
Though the values of some fields in the header might be redundant, it is
not possible to omit any fields.
```

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From: Dmitri Tikhonov <[email-masked]>
Date: Fri, 13 Sep 2019 07:52:37 -0700

@RyanAtGoogle writes:
> The first sentence says, "complete" but that might be open to interpretation. The second sentence makes it clear what that means. I like it.

The third sentence clarifies the first sentence well, too.

I would just drop the second sentence altogether.

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From: Jana Iyengar <[email-masked]>
Date: Mon, 16 Sep 2019 16:40:19 -0700

I can't remember now, but we did have an intermediate design where redundant fields were absent. This sentence may have crept in around then. I agree with @dtikhonov : it does seem redundant now.

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From: Martin Thomson <[email-masked]>
Date: Mon, 16 Sep 2019 16:55:40 -0700

Closed #3029 via #3040.

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