Robert Wilton's Discuss on draft-ietf-quic-invariants-12: (with DISCUSS)

Robert Wilton via Datatracker <> Mon, 04 January 2021 11:42 UTC

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Subject: Robert Wilton's Discuss on draft-ietf-quic-invariants-12: (with DISCUSS)
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Robert Wilton has entered the following ballot position for
draft-ietf-quic-invariants-12: Discuss

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A trivial discuss that should hopefully be easy to resolve, and it is plausible
that the resolution may end up being in the QUIC transport document:

In this document, the unused bits are defined as:

                   Figure 4: Version Negotiation Packet

   Only the most significant bit of the first byte of a Version
   Negotiation packet has any defined value.  The remaining 7 bits,
   labeled Unused, can be set to any value when sending and MUST be
   ignored on receipt.

In the QUIC transport document, they are defined as this:

                   Figure 14: Version Negotiation Packet

   The value in the Unused field is selected randomly by the server.
   Clients MUST ignore the value of this field.  Servers SHOULD set the
   most significant bit of this field (0x40) to 1 so that Version
   Negotiation packets appear to have the Fixed Bit field.

I would have expected that these two should be consistent as to whether the
Fixed Bit SHOULD be set to 1 or not.  Given draft-thomson-quic-bit-grease-00,
it might be better if the SHOULD is removed from QUIC transport, but I will
defer to the experts here.