Greasing the QUIC Bit
draft-ietf-quic-bit-grease-04

[Ballot comment]
Clearing discuss based on proposed updates from Martin Thompson.



(1) The purpose of having a fixed value is to allow QUIC to be
  efficiently distinguished from other protocols;

This sentence seems inconsistent with draft-ietf-quic-manageability that states that this bit cannot be used reliably to indicate QUIC traffic.

draft-ietf-quic-manageability states:
  The QUIC wire image is not specifically designed to be
  distinguishable from other UDP traffic by a passive observer in the
  network.  While certain QUIC applications may be heuristically
  identifiable on a per-application basis, there is no general method
  for distinguishing QUIC traffic from otherwise-unclassifiable UDP
  traffic on a given link.  Any unrecognized UDP traffic may therefore
  be QUIC traffic.

  *  "fixed bit": The second-most-significant bit of the first octet of
      most QUIC packets of the current version is set to 1, enabling
      endpoints to demultiplex with other UDP-encapsulated protocols.
      Even though this bit is fixed in the version 1 specification,
      endpoints might use an extension that varies the bit.  Therefore,
      observers cannot reliably use it as an identifier for QUIC.

Ultimately, for QUIC, it isn't really clear to me whether:
(i) Intermediates nodes are not expected to be able to efficiently identify QUIC traffic.
(ii) Intermediate nodes are expected to efficiently identify QUIC v1 traffic only.

Assuming that the quic bit grease extension ends up with reasonable deployment then I think that we end up with (i).  Is that correct and the intention?

(2)
This document already has a comment in the security section about the potential security impact of using this extension.  I think that this document could benefit from an Operational Considerations section to highlight that using this extension is likely to impact the ability of intermediate devices to identify QUIC packets which may change how the network handles QUIC packets, either by giving them special treatment compared to other UDP traffic, or categorizing them and handling them the same as all other UDP traffic.  Or perhaps the security section paragraph could be expanded to cover this point (although it isn't really security, but observed functionality).

[Ballot discuss]
Thanks for the work on this document,

Hopefully this discuss will be relatively easy to resolve - and may result from a lack of understanding - but -

  Endpoints that receive the grease_quic_bit transport parameter from a
  peer SHOULD set the QUIC Bit to an unpredictable value unless another
  extension assigns specific meaning to the value of the bit.

Now, this is in reference to a bit - which can only be 0 or 1 - and the document further goes on to clarify certain situations where this bit should be set or unset - so I am not at all sure what this paragraph really means and hoping this can be clarified because I'm not sure how this will be interpreted on implementation.

[Ballot discuss]
Hi,

Sorry for the late DISCUSS, and hopefully not tricky to resolve, but there are two points that I think it would be helpful to clarify:

(1) Ensuring the language is consistent with draft-ietf-quic-manageability.
(2) Possibly whether a short Operational Considerations section could/should be added.

Details in the comments.

Regards,
Rob

[Ballot comment]
(1) The purpose of having a fixed value is to allow QUIC to be
  efficiently distinguished from other protocols;

This sentence seems inconsistent with draft-ietf-quic-manageability that states that this bit cannot be used reliably to indicate QUIC traffic.

draft-ietf-quic-manageability states:
  The QUIC wire image is not specifically designed to be
  distinguishable from other UDP traffic by a passive observer in the
  network.  While certain QUIC applications may be heuristically
  identifiable on a per-application basis, there is no general method
  for distinguishing QUIC traffic from otherwise-unclassifiable UDP
  traffic on a given link.  Any unrecognized UDP traffic may therefore
  be QUIC traffic.

  *  "fixed bit": The second-most-significant bit of the first octet of
      most QUIC packets of the current version is set to 1, enabling
      endpoints to demultiplex with other UDP-encapsulated protocols.
      Even though this bit is fixed in the version 1 specification,
      endpoints might use an extension that varies the bit.  Therefore,
      observers cannot reliably use it as an identifier for QUIC.

Ultimately, for QUIC, it isn't really clear to me whether:
(i) Intermediates nodes are not expected to be able to efficiently identify QUIC traffic.
(ii) Intermediate nodes are expected to efficiently identify QUIC v1 traffic only.

Assuming that the quic bit grease extension ends up with reasonable deployment then I think that we end up with (i).  Is that correct and the intention?

(2)
This document already has a comment in the security section about the potential security impact of using this extension.  I think that this document could benefit from an Operational Considerations section to highlight that using this extension is likely to impact the ability of intermediate devices to identify QUIC packets which may change how the network handles QUIC packets, either by giving them special treatment compared to other UDP traffic, or categorizing them and handling them the same as all other UDP traffic.  Or perhaps the security section paragraph could be expanded to cover this point (although it isn't really security, but observed functionality).

[Ballot comment]
Apologies for not being able to do a more in-depth review, I'm currently traveling (an emergency trip to South Africa), and so am relying on Scott Bradner's OpsDir review (https://datatracker.ietf.org/doc/review-ietf-quic-bit-grease-04-opsdir-telechat-bradner-2022-06-14/).

I'd like to thank Scott and the authors for addressing Scott's comments in the -03 version and to Scott for updating it for -04.
Like Scott I really think that this should use the Updates tag - yes, Updates is very poorly defined, and perhaps we should have a "See Also" / "Worth Reading" / "Closely Related" / "If you enjoyed this RFC, you may also enjoy these other ones" / "NOTICE TO IMPLEMENTERS: See RFCxxxx" tags -- but without them, we use Updates for this. I'll be on a plane during the telechat, but I urge the rest of the IESG to discuss / consider this...

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

The IANA Functions Operator has completed its review of draft-ietf-quic-bit-grease-03. If any part of this review is inaccurate, please let us know.

The IANA Functions Operator understands that, upon approval of this document, there is a single action which we must complete.

In the QUIC Transport Parameters registry on the QUIC registry page located at:

https://www.iana.org/assignments/quic/

a new registration will be made as follows:

Value: 0x2ab2
Parameter Name: grease_quic_bit
Status: Permanent
Specification: [ RFC-to-be ]
Date: [ TBD-at-Registration ]
Change Controller: IETF
Contact: QUIC WG
Notes:

The IANA Functions Operator understands that this is the only action required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is meant only to confirm the list of actions that will be performed.

For definitions of IANA review states, please see:

https://datatracker.ietf.org/help/state/draft/iana-review

Thank you,

Michelle Thangtamsatid
IANA Services Specialist

The following Last Call announcement was sent out (ends 2022-06-01):

From: The IESG
To: IETF-Announce
CC: Zaheduzzaman.Sarker@ericsson.com, draft-ietf-quic-bit-grease@ietf.org, lucaspardue.24.7@gmail.com, quic-chairs@ietf.org, quic@ietf.org
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Greasing the QUIC Bit) to Proposed Standard


The IESG has received a request from the QUIC WG (quic) to consider the
following document: - 'Greasing the QUIC Bit'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
last-call@ietf.org mailing lists by 2022-06-01. Exceptionally, comments may
be sent to iesg@ietf.org instead. In either case, please retain the beginning
of the Subject line to allow automated sorting.

Abstract


  This document describes a method for negotiating the ability to send
  an arbitrary value for the second-to-most significant bit in QUIC
  packets.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-quic-bit-grease/



No IPR declarations have been submitted directly on this I-D.

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up. Changes are expected over time.

This version is dated 1 November 2019.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
Standard, Informational, Experimental, or Historic)? Why is this the proper type
of RFC? Is this type of RFC indicated in the title page header?

Proposed Standard. This is the proper type for a simple extension to the use of
the QUIC wire image.

(2) The IESG approval announcement includes a Document Announcement Write-Up.
Please provide such a Document Announcement Write-Up. Recent examples can be
found in the "Action" announcements for approved documents. The approval
announcement contains the following sections:

Technical Summary:

The "wire image" of QUIC packets is described in QUIC invariants (RFC 8999).
Little about this image is visible to passive observers. One field, the
so-called QUIC Bit, resides at the second-to-most significant bit of the first
byte of every QUIC packet. RFC 9000 requires the QUIC Bit to be set to a value
of 1, with the purpose being to allow QUIC traffic to be easily distinguisable
from some other UDP-based traffic when they share a UDP port. This document
defines a behavioural extension, negotiated using transport parameters, that
permits endpoints to use any value for this bit. The intention of this extension
is to exercise variation in the wire image (i.e, "Grease" the QUIC Bit) in order
to support future QUIC changes before systems ossify (see RFC 9170 for more
background).

Working Group Summary:

The document is succinct. During adoption and WGLC there was sufficient review
and no major issues were raised or incidents occured.

Document Quality:

The document is succinct and describes how to vary one bit, using
well-established mechanisms. There are several implementations of the grease bit
extension and several interoperable deployments deployed on the Internet.

No special review has been required.

Personnel:

Lucas Pardue is the document shepherd. Zahed Sarker is the AD.

(3) Briefly describe the review of this document that was performed by the
Document Shepherd. If this version of the document is not ready for publication,
please explain why the document is being forwarded to the IESG.

I have reviewed this document thoroughly and personally implemented the
extension, which took 4 hours including testing. The scope of the extension is
focused, and is straightforward to implement for any person familiar with QUIC.

(4) Does the document Shepherd have any concerns about the depth or breadth of
the reviews that have been performed?

No

(5) Do portions of the document need review from a particular or from broader
perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or
internationalization? If so, describe the review that took place.

No special review is required.

(6) Describe any specific concerns or issues that the Document Shepherd has with
this document that the Responsible Area Director and/or the IESG should be aware
of? For example, perhaps he or she is uncomfortable with certain parts of the
document, or has concerns whether there really is a need for it. In any event,
if the WG has discussed those issues and has indicated that it still wishes to
advance the document, detail those concerns here.

No specific concerns.

(7) Has each author confirmed that any and all appropriate IPR disclosures
required for full conformance with the provisions of BCP 78 and BCP 79 have
already been filed. If not, explain why?

Yes. There are no IPR disclosures for this document.

(8) Has an IPR disclosure been filed that references this document? If so,
summarize any WG discussion and conclusion regarding the IPR disclosures.

There are no IPR disclosures for this document.

(9) How solid is the WG consensus behind this document? Does it represent the
strong concurrence of a few individuals, with others being silent, or does the
WG as a whole understand and agree with it?

The extension defined in this document has been implemented and deployed by a
wide range of vendors. There is strong consensus on the document, with no
dissent raised during the process.

(10) Has anyone threatened an appeal or otherwise indicated extreme discontent?
If so, please summarise the areas of conflict in separate email messages to the
Responsible Area Director. (It should be in a separate email because this
questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this document. (See
http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist).
Boilerplate checks are not enough; this check needs to be thorough.

No nits.

(12) Describe how the document meets any required formal review criteria, such
as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

N/A

(13) Have all references within this document been identified as either
normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative references
exist, what is the plan for their completion?

No.

(15) Are there downward normative references references (see RFC 3967)? If so,
list these downward references to support the Area Director in the Last Call
procedure.

No.

(16) Will publication of this document change the status of any existing RFCs?
Are those RFCs listed on the title page header, listed in the abstract, and
discussed in the introduction? If the RFCs are not listed in the Abstract and
Introduction, explain why, and point to the part of the document where the
relationship of this document to the other RFCs is discussed. If this
information is not in the document, explain why the WG considers it unnecessary.

No.

(17) Describe the Document Shepherd's review of the IANA considerations section,
especially with regard to its consistency with the body of the document. Confirm
that all protocol extensions that the document makes are associated with the
appropriate reservations in IANA registries. Confirm that any referenced IANA
registries have been clearly identified. Confirm that newly created IANA
registries include a detailed specification of the initial contents for the
registry, that allocations procedures for future registrations are defined, and
a reasonable name for the new registry has been suggested (see RFC 8126).

This document registers a new Transport Parameter. This is a permanent
registration, greater than 0x3f, which operates uner the Specification Required
policy.

The registration conforms to the registration requirements of IANA.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find useful in
selecting the IANA Experts for these new registries.

N/A

(19) Describe reviews and automated checks performed by the Document Shepherd to
validate sections of the document written in a formal language, such as XML
code, BNF rules, MIB definitions, YANG modules, etc.

N/A

(20) If the document contains a YANG module, has the module been checked with
any of the recommended validation tools
(https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module comply
with the Network Management Datastore Architecture (NMDA) as specified in
RFC8342?

N/A

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up. Changes are expected over time.

This version is dated 1 November 2019.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
Standard, Informational, Experimental, or Historic)? Why is this the proper type
of RFC? Is this type of RFC indicated in the title page header?

Proposed Standard. This is the proper type for a simple extension to the use of
the QUIC wire image.

(2) The IESG approval announcement includes a Document Announcement Write-Up.
Please provide such a Document Announcement Write-Up. Recent examples can be
found in the "Action" announcements for approved documents. The approval
announcement contains the following sections:

Technical Summary:

The "wire image" of QUIC packets is described in QUIC invariants (RFC 8999).
Little about this image is visible to passive observers. One field, the
so-called QUIC Bit, resides at the second-to-most significant bit of the first
byte of every QUIC packet. RFC 9000 requires the QUIC Bit to be set to a value
of 1, with the purpose being to allow QUIC traffic to be easily distinguisable
from some other UDP-based traffic when they share a UDP port. This document
defines a behavioural extension, negotiated using transport parameters, that
permits endpoints to use any value for this bit. The intention of this extension
is to exercise variation in the wire image (i.e, "Grease" the QUIC Bit) in order
to support future QUIC changes before systems ossify (see RFC 9170 for more
background).

Working Group Summary:

The document is succinct. During adoption and WGLC there was sufficient review
and no major issues were raised or incidents occured.

Document Quality:

The document is succinct and describes how to vary one bit, using
well-established mechanisms. There are several implementations of the grease bit
extension and several interoperable deployments deployed on the Internet.

No special review has been required.

Personnel:

Lucas Pardue is the document shepherd. Zahed Sarker is the AD.

(3) Briefly describe the review of this document that was performed by the
Document Shepherd. If this version of the document is not ready for publication,
please explain why the document is being forwarded to the IESG.

I have reviewed this document thoroughly and personally implemented the
extension, which took 4 hours including testing. The scope of the extension is
focused, and is straightforward to implement for any person familiar with QUIC.

(4) Does the document Shepherd have any concerns about the depth or breadth of
the reviews that have been performed?

No

(5) Do portions of the document need review from a particular or from broader
perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or
internationalization? If so, describe the review that took place.

No special review is required.

(6) Describe any specific concerns or issues that the Document Shepherd has with
this document that the Responsible Area Director and/or the IESG should be aware
of? For example, perhaps he or she is uncomfortable with certain parts of the
document, or has concerns whether there really is a need for it. In any event,
if the WG has discussed those issues and has indicated that it still wishes to
advance the document, detail those concerns here.

No specific concerns.

(7) Has each author confirmed that any and all appropriate IPR disclosures
required for full conformance with the provisions of BCP 78 and BCP 79 have
already been filed. If not, explain why?

Yes. There are no IPR disclosures for this document.

(8) Has an IPR disclosure been filed that references this document? If so,
summarize any WG discussion and conclusion regarding the IPR disclosures.

There are no IPR disclosures for this document.

(9) How solid is the WG consensus behind this document? Does it represent the
strong concurrence of a few individuals, with others being silent, or does the
WG as a whole understand and agree with it?

The extension defined in this document has been implemented and deployed by a
wide range of vendors. There is strong consensus on the document, with no
dissent raised during the process.

(10) Has anyone threatened an appeal or otherwise indicated extreme discontent?
If so, please summarise the areas of conflict in separate email messages to the
Responsible Area Director. (It should be in a separate email because this
questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this document. (See
http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist).
Boilerplate checks are not enough; this check needs to be thorough.

No nits.

(12) Describe how the document meets any required formal review criteria, such
as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

N/A

(13) Have all references within this document been identified as either
normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative references
exist, what is the plan for their completion?

No.

(15) Are there downward normative references references (see RFC 3967)? If so,
list these downward references to support the Area Director in the Last Call
procedure.

No.

(16) Will publication of this document change the status of any existing RFCs?
Are those RFCs listed on the title page header, listed in the abstract, and
discussed in the introduction? If the RFCs are not listed in the Abstract and
Introduction, explain why, and point to the part of the document where the
relationship of this document to the other RFCs is discussed. If this
information is not in the document, explain why the WG considers it unnecessary.

No.

(17) Describe the Document Shepherd's review of the IANA considerations section,
especially with regard to its consistency with the body of the document. Confirm
that all protocol extensions that the document makes are associated with the
appropriate reservations in IANA registries. Confirm that any referenced IANA
registries have been clearly identified. Confirm that newly created IANA
registries include a detailed specification of the initial contents for the
registry, that allocations procedures for future registrations are defined, and
a reasonable name for the new registry has been suggested (see RFC 8126).

This document registers a new Transport Parameter. This is a permanent
registration, greater than 0x3f, which operates uner the Specification Required
policy.

The registration conforms to the registration requirements of IANA.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find useful in
selecting the IANA Experts for these new registries.

N/A

(19) Describe reviews and automated checks performed by the Document Shepherd to
validate sections of the document written in a formal language, such as XML
code, BNF rules, MIB definitions, YANG modules, etc.

N/A

(20) If the document contains a YANG module, has the module been checked with
any of the recommended validation tools
(https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module comply
with the Network Management Datastore Architecture (NMDA) as specified in
RFC8342?

N/A