Fast Recovery for EVPN Designated Forwarder Election
draft-ietf-bess-evpn-fast-df-recovery-12

[Ballot comment]
Thanks for the updates! Looks good, modulo two comments, on the new text.

## COMMENTS

### Section 2.2, SHOULD validate

        implementations SHOULD validate the received
  SCT against an upper-bound

Considering that the upper bound validation is important for the solution’s security (isn’t it?) I am wondering why this is not MUST. Indeed, just a few lines down we have,

                                  A PE which receives an SCT
  representing an offset larger than the local peering timer MUST
  discard the Service Carving Time and SHALL treat the DF Election at
  the peer as having occurred already, as above.

This suggests that the quoted SHOULD is an oversight.

## NITS

### Section 2

“may to make” -> “may make”

[Ballot comment]
A minor point: The Terminology section defines SCT as "Service Carving Timestamp", but the rest of the document calls it the "Service Carving Time".

[Ballot comment]
Thanks for working on this specification.

I have no comments from transport protocol point of view. However, I am missing how the skew (in section 3) will be calculated. Is this well defined? Is there a scenario where more than one PEs take over if PE2 (in the example) fails? if yes, how would then the skewing work?

[Ballot comment]
Thank you to Elwyn Davies for the GENART review.

** Section 2.1
  A DF
  Election operation occurring exactly at the Era transition boundary
  some time in 2036 is outside of the scope of this document.

How should this scoping be interpreted?  Is it saying that this protocol will misbehave in some way around the 2036 boundary?  Is there an operational consideration for deployments for that short time?

[Ballot discuss]
# John Scudder, RTG AD, comments for draft-ietf-bess-evpn-fast-df-recovery-10
CC @jgscudder

Thanks for this document. I appreciate the fact it was straightforward to read and review, and of course, I appreciate the work on a useful protocol extension!

My earlier ballot, despite what I noted in the header, was actually a review of version 9, not version 10. Looking at the document history, the version changed out from under me sometime during the day, after I had mostly completed my review but before I submitted it. I cut and pasted the document name without noticing. I'm sorry for the oversight and hope I didn't cause anyone extra work. I see that version 10 fixes many of the things I commented/discussed on (probably due to Toerless Eckert's iotdir review which raised many of the same issues). Having now read Toerless's review and Luc André's reply (I could have saved myself some work if I'd read them earlier!) I've revised my ballot accordingly. It also seems as though the conversation with Toerless is still in flight, so my assumption is there may be more updates to the document as that conversation unfolds.

I also hope you'll be addressing Ines Robles' RTGDIR review. It looks like Ines has overlapping concerns with the ones Toerless and I raised, and some others too.

## DISCUSS

I have two concerns I'd (still) like to discuss.

### "Unreasonable" SCT offsets

Apart from a few words in the Security Considerations section, you don't provide any instructions to the implementer about what to do with unreasonable SCT offsets, in particular unreasonable SCT future offsets (see also Ines' review). The language from Section 5 is,

  It is left to implementations to
  decide what consists an "unreasonably large" SCT value.

The quotation marks imply that you think the implementor should do something about unreasonably large SCT values, but the spec doesn't supply any clarity about it. That's too bad, it should. I accept the argument in the preceding Security Considerations sentences (not quoted) that the ability to signal unreasonable SCT values doesn't introduce a new vulnerability vis-à-vis the pre-existing specifications. Nonetheless, it does seem like this specification should advise implementers to impose an upper limit on what SCT future offset they will accept. The quoted sentence is a backhanded hint in that direction. I think you should make it explicit, probably in Section 2 since that seems to be where elements of procedure mostly go (see also my later remarks about this in the COMMENTS section).

I see that you've revised Section 2.2 compared to my earlier review of version 9. It looks as though it could use a little more work, though, to capture two things: First and most importantly, explicitly introduce the idea of a maximum acceptable SCT offset (what I called max_SCT_offset in my earlier ballot). Second, explicitly address the case where SCT minus skew is in the past. Sure, the latter is "obvious", but one of our goals in writing specifications is to be thorough, so IMO this is worth capturing (it isn't DISCUSS-worthy in itself, I mention it here only because it's part of the same section).

### Assumptions about synchronized clocks

Although the document assumes synchronized clocks, it doesn't provide any details about its assumptions, e.g. how close synchronization needs to be and what the consequences are if the requirement isn't met. Normally, specifications assuming synchronized clocks will provide at least some basic analysis.

I think probably if you fix the max_SCT_delay thing, the analysis would be easy because it would in effect bound the maximum effect of clock desynchronization, and I bet the analysis would amount to "if you have badly desynchronized clocks, it acts like RFC7432." (But this is just a guess, you are the experts.)

If you choose to add a short analysis, I could see it being a bullet in Section 1.4.

(I do see both Ines and Toerless raised some related concerns in their reviews, although not this exact question AFAICT.)

[Ballot comment]
## COMMENTS

### Section 3, peering timer

A new issue I noticed in version 10 is that you've added this paragraph:

  The peering timer is a configurable value where 3 seconds represents
  the default.  Configuring a timer value of 0, or so small as to
  expire during propagation of the BGP routes, is outside the scope of
  this document.  In reality, the use of the SCT approach presented in
  this documents encourages the use of larger peering timer values to
  overcome any sort of BGP route propagation delays.

However, this is the only place the document refers to a "peering timer". Thanks for the clarifying paragraph, it's good. But I think you should do something to clear up the terminology ambiguity. For example, everywhere you're referring to this timer, you could use the term "peering timer" instead of just "timer", and you could add it to your terminology section, along with a reference to RFC 7432 Section 8.5 step (2).

(Also, s/this documents/this document/)

### Section 1.4, this sentence no verb

(fixed in 10)

### Section 1.4, "normalizes"

(fixed in 10)

### Sections 2 and 3 aren't well-divided

Section 2 is called "DF Election Synchronization Solution". Based on that, I would assume that the entire solution would be specified in this section and its subsections. Section 3 is called "Synchronization Scenarios". Based on that, I would assume it contains examples, intended to help the reader understand the operation of the solution.

Unfortunately, that's not entirely the case. Section 3 contains instances of normative, or should-be-normative, text. I think you should restructure these two sections to put the entire solution in Section 2 and keep Section 3 as examples. By the way, I did find the examples very useful, thank you for including them. I've flagged suggestions for restructuring in other more specific comments.

For that matter, there's also normative text in Section 5: "the receiving PE SHALL treat the DF Election at the peer as having occurred already, and proceed without starting any timer to futher delay service carving". That's not a consideration, that's a requirement, and I think it should also go into Section 2. The approach suggested in my DISCUSS would fix this issue. (Also s/futher/further/.)

### Section 2, several things about skew

(fixed in 10)

### Section 2.1, that's not 8 octets

```
  A new BGP extended community is defined to communicate the Service
  Carving Timestamp for each Ethernet Segment.

  A new transitive extended community where the Type field is 0x06, and
  the Sub-Type is 0x0F is advertised along with the Ethernet Segment
  route.  The expected Service Carving Time is encoded as an 8-octet
  value as follows:

                        1                  2                  3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | Type = 0x06  | Sub-Type(0x0F)|      Timestamp Seconds        ~
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  ~  Timestamp Seconds            | Timestamp Fractional Seconds  |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
```

Did you mean six octets? Because that’s what the diagram shows... unless you're calling 0x060F part of the service carving time, which doesn't make much sense. I don't know, maybe you meant that it's an eight-octet value encoded in six octets, but you explain that just fine in the text that follows. I think you'd be better off simplifying the introductory text to something like this,

NEW:
  A BGP extended community, with Type 0x06 and Sub-Type 0x0F, is defined
  to communicate the Service Carving Timestamp for each Ethernet Segment:
 
                        1                  2                  3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | Type = 0x06  | Sub-Type(0x0F)|      Timestamp Seconds        ~
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  ~  Timestamp Seconds            | Timestamp Fractional Seconds  |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Note I also elided "new" because fairly soon after publication as an RFC, the community will no longer be "new". Then you let the following text supply the additional detail that I've removed from my NEW text.

### Section 2.1, "outside of the scope of this document"

“A DF Election operation occurring exactly at the Era transition boundary some time in 2036 is outside of the scope of this document.”

That’s fine as long as the consequences of such an incident wouldn’t be serious. Have you analyzed this? A few words to this effect would be desirable; the rollover is less than twelve years in the future and your specification is likely to still be in use then.

I bet that, again, the change suggested in my DISCUSS would make this easy to cover because even a naïve implementation would treat era rollover as nothing worse than severe clock skew, and the window of vulnerability would be bounded to max_SCT_delay. I'd still encourage you to say a few words about it, to console any readers doing a Y2036 review sometime in the future.

### Section 3.1, concurrent elections

  In the case of multiple concurrent DF elections, each initiated by
  one of the recovering PEs, the SCTs must be ordered chronologically.
  All PEs shall execute only a single DF Election at the service
  carving time corresponding to the largest (latest) received timestamp
  value.  This DF Election will involve all active PEs in a unified DF
  Election update.

This looks and feels exactly like normative specification, which makes me think it belongs in Section 2. I also wonder if you want SHALL instead of "shall".

## Notes

This review is in the ["IETF Comments" Markdown format][ICMF], You can use the
[`ietf-comments` tool][ICT] to automatically convert this review into
individual GitHub issues.

[ICMF]: https://github.com/mnot/ietf-comments/blob/main/format.md
[ICT]: https://github.com/mnot/ietf-comments

[Ballot discuss]
# John Scudder, RTG AD, comments for draft-ietf-bess-evpn-fast-df-recovery-10
CC @jgscudder

Thanks for this document. I appreciate the fact it was straightforward to read and review, and of course, I appreciate the work on a useful protocol extension!

## DISCUSS

I have two concerns I'd like to discuss.

### "Unreasonable" SCT offsets

Apart from a few words in the Security Considerations section, you don't provide any instructions to the implementer about what to do with unreasonable SCT offsets, in particular unreasonable SCT future offsets. The language from Section 5 is,

  It is left to implementations to
  decide what consists an "unreasonably large" SCT value.

The quotation marks imply that you think the implementor should do something about unreasonably large SCT values, but the spec doesn't supply any clarity about it. That's too bad, it should. I accept the argument in the preceding Security Considerations sentences (not quoted) that the ability to signal unreasonable SCT values doesn't introduce a new vulnerability vis-à-vis the pre-existing specifications. Nonetheless, it does seem like this specification should advise implementers to impose an upper limit on what SCT future offset they will accept. The quoted sentence is a backhanded hint in that direction. I think you should make it explicit, probably in Section 2 since that seems to be where elements of procedure mostly go (see also my later remarks about this in the COMMENTS section).

One way to address this would be to insert something into Section 2.2, along the lines of,

  - Initialize SCT_delay to 0.
  - If an SCT timestamp is present (etc etc), then,
    - If the SCT timestamp is further in the future than max_SCT_delay,
      SCT_delay = max_SCT_delay.
    - If the SCT timestamp is less than SCT_skew time units in the future,
      SCT_delay = 0. (This includes the case where it is in the past.)
    - Else SCT_delay = (SCT timestamp value) - (present time) - SCT_skew

and then write 9.1 in terms of "wait SCT_delay before proceeding to 9.2".

This is crudely written, I don't expect you to use the text above, although you're welcome to if you want. I'm just trying to demonstrate one way to close the gap.

In addition to inventing SCT_delay and max_SCT_delay, I've incorporated skew into the above (and renamed it SCT_skew). An underspecification of skew is another, lesser, concern I had (see COMMENTS) and this seemed the natural place to work it in.

### Assumptions about synchronized clocks

Although the document assumes synchronized clocks, it doesn't provide any details about its assumptions, e.g. how close synchronization needs to be and what the consequences are if the requirement isn't met. Normally, specifications assuming synchronized clocks will provide at least some basic analysis.

I think probably if you fix the max_SCT_delay thing, the analysis would be easy because it would in effect bound the maximum effect of clock desynchronization, and I bet the analysis would amount to "if you have badly desynchronized clocks, it acts like RFC7432." (But this is just a guess, you are the experts.)

If you choose to add a short analysis, I could see it being a bullet in Section 1.4.

[Ballot discuss]
# John Scudder, RTG AD, comments for draft-ietf-bess-evpn-fast-df-recovery-10
CC @jgscudder

Thanks for this document. I appreciate the fact it was straightforward to read and review, and of course, I appreciate the work on a useful protocol extension!

## DISCUSS

I have two concerns I'd like to discuss.

### "Unreasonable" SCT offsets

Apart from a few words in the Security Considerations section, you don't provide any instructions to the implementer about what to do with unreasonable SCT offsets, in particular unreasonable SCT future offsets. The language from Section 5 is,

  It is left to implementations to
  decide what consists an "unreasonably large" SCT value.

The quotation marks imply that you think the implementor should do something about unreasonably large SCT values, but the spec doesn't supply any clarity about it. That's too bad, it should. I accept the argument in the preceding Security Considerations sentences (not quoted) that the ability to signal unreasonable SCT values doesn't introduce a new vulnerability vis-à-vis the pre-existing specifications. Nonetheless, it does seem like this specification should advise implementers to impose an upper limit on what SCT future offset they will accept. The quoted sentence is a backhanded hint in that direction. I think you should make it explicit, probably in Section 2 since that seems to be where elements of procedure mostly go (see also my later remarks about this in the COMMENTS section).

One way to address this would be to insert something into Section 2.2, along the lines of,

  - Initialize SCT_delay to 0.
  - If an SCT timestamp is present (etc etc), then,
    - If the SCT timestamp is further in the future than max_SCT_delay,
      SCT_delay = max_SCT_delay.
    - If the SCT timestamp is less than SCT_skew time units in the future,
      SCT_delay = 0. (This includes the case where it is in the past.)
    - Else SCT_delay = (SCT timestamp value) - (present time) - SCT_skew

and then write 9.1 in terms of "wait SCT_delay before proceeding to 9.2".

This is crudely written, I don't expect you to use the text above, although you're welcome to if you want. I'm just trying to demonstrate one way to close the gap.

In addition to inventing SCT_delay and max_SCT_delay, I've incorporated skew into the above (and renamed it SCT_skew). An underspecification of skew is another, lesser, concern I had (see COMMENTS) and this seemed the natural place to work it in.

### Assumptions about synchronized clocks

Although the document assumes synchronized clocks, it doesn't provide any details about its assumptions, e.g. how close synchronization needs to be and what the consequences are if the requirement isn't met. Normally, specifications assuming synchronized clocks will provide at least some basic analysis.

I think probably if you fix the max_SCT_delay thing, the analysis would be easy because it would in effect bound the maximum effect of clock desynchronization, and I bet the analysis would amount to "if you don't have badly desynchronized clocks, it acts like RFC7432." (But this is just a guess, you are the experts.)

If you choose to add a short analysis, I could see it being a bullet in Section 1.4.

[Ballot comment]
## COMMENTS

### Section 1.4, this sentence no verb

  *  The fast DF recovery solution maintains backwards-compatibility
      (see Section 4) by ensuring that PEs any unrecognized new BGP
      Extended Community.

The second clause should have a verb, but it doesn't. I'd propose a rewrite if I knew what you were trying to say.

### Section 1.4, "normalizes"

  *  The fast DF recovery solution is agnostic of the actual time
      synchronization mechanism used, and normalizes to NTP for EVPN
      signalling only.

I don't understand what you mean by this, in particular by "normalizes to NTP for EVPN signalling only". Can you rephrase it? (Also, BTW, "signaling" has only one ell.)

### Sections 2 and 3 aren't well-divided

Section 2 is called "DF Election Synchronization Solution". Based on that, I would assume that the entire solution would be specified in this section and its subsections. Section 3 is called "Synchronization Scenarios". Based on that, I would assume it contains examples, intended to help the reader understand the operation of the solution.

Unfortunately, that's not entirely the case. Section 3 contains instances of normative, or should-be-normative, text. I think you should restructure these two sections to put the entire solution in Section 2 and keep Section 3 as examples. By the way, I did find the examples very useful, thank you for including them. I've flagged suggestions for restructuring in other more specific comments.

For that matter, there's also normative text in Section 5: "the receiving PE SHALL treat the DF Election at the peer as having occurred already, and proceed without starting any timer to futher delay service carving". That's not a consideration, that's a requirement, and I think it should also go into Section 2. The approach suggested in my DISCUSS would fix this issue. (Also s/futher/further/.)

### Section 2, several things about skew

  The receiving partner PEs add a skew (default = -10ms) to
  the Service Carving Time to enforce this mechanism.  The previously
  inserted PE(s) must perform service carving first, followed shortly
  by the newly insterted PE, after the specified skew delay.
 
The first sentence says that the default is -10 ms, so the receiving partner adds -10 ms, or more simply put, the receiving partner subtracts 10 ms. I think the whole quote holds together but it’s unnecessarily hard to follow. Perhaps something as basic as,

NEW:
  The receiving partner PEs subtract a skew (default = 10ms) from
  the Service Carving Time to enforce this mechanism.  The previously
  inserted PE(s) must perform service carving first, followed shortly
  by the newly inserted PE, after the specified skew delay.

Note I also made the correction s/insterted/inserted/

Of somewhat greater concern, I don't think Section 2 is precise enough about when and how the skew is applied. It's possible to work it out by referring to the example in Section 3, but it shouldn't be necessary to do this to glean what an implementation MUST do.

The approach suggested in my DISCUSS would probably make the problem go away.

### Section 2.1, that's not 8 octets

```
  A new BGP extended community is defined to communicate the Service
  Carving Timestamp for each Ethernet Segment.

  A new transitive extended community where the Type field is 0x06, and
  the Sub-Type is 0x0F is advertised along with the Ethernet Segment
  route.  The expected Service Carving Time is encoded as an 8-octet
  value as follows:

                        1                  2                  3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | Type = 0x06  | Sub-Type(0x0F)|      Timestamp Seconds        ~
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  ~  Timestamp Seconds            | Timestamp Fractional Seconds  |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
```

Did you mean six octets? Because that’s what the diagram shows... unless you're calling 0x060F part of the service carving time, which doesn't make much sense. I don't know, maybe you meant that it's an eight-octet value encoded in six octets, but you explain that just fine in the text that follows. I think you'd be better off simplifying the introductory text to something like this,

NEW:
  A BGP extended community, with Type 0x06 and Sub-Type 0x0F, is defined
  to communicate the Service Carving Timestamp for each Ethernet Segment:
 
                        1                  2                  3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | Type = 0x06  | Sub-Type(0x0F)|      Timestamp Seconds        ~
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  ~  Timestamp Seconds            | Timestamp Fractional Seconds  |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Note I also elided "new" because fairly soon after publication as an RFC, the community will no longer be "new". Then you let the following text supply the additional detail that I've removed from my NEW text.

### Section 2.1, "outside of the scope of this document"

“A DF Election operation occurring exactly at the Era transition boundary some time in 2036 is outside of the scope of this document.”

That’s fine as long as the consequences of such an incident wouldn’t be serious. Have you analyzed this? A few words to this effect would be desirable; the rollover is less than twelve years in the future and your specification is likely to still be in use then.

I bet that, again, the change suggested in my DISCUSS would make this easy to cover because even a naïve implementation would treat era rollover as nothing worse than severe clock skew, and the window of vulnerability would be bounded to max_SCT_delay. I'd still encourage you to say a few words about it, to console any readers doing a Y2036 review sometime in the future.

### Section 3.1, concurrent elections

  In the case of multiple concurrent DF elections, each initiated by
  one of the recovering PEs, the SCTs must be ordered chronologically.
  All PEs shall execute only a single DF Election at the service
  carving time corresponding to the largest (latest) received timestamp
  value.  This DF Election will involve all active PEs in a unified DF
  Election update.

This looks and feels exactly like normative specification, which makes me think it belongs in Section 2. I also wonder if you want SHALL instead of "shall".

## Notes

This review is in the ["IETF Comments" Markdown format][ICMF], You can use the
[`ietf-comments` tool][ICT] to automatically convert this review into
individual GitHub issues.

[ICMF]: https://github.com/mnot/ietf-comments/blob/main/format.md
[ICT]: https://github.com/mnot/ietf-comments

[Ballot comment]
Thanks to Dave Thaler for the INTDIR, to Elwyn Davies for the GENART, and Toerless for the IOTDIR review, the last of which surprised me also. But thanks to Toerless for his review all the same.

Several others have provided COMMENTs that I had, so I am not going to repeat them here. Some of the following NITS may also be duplicates.

-------------------------------------------------------------------------------
NIT
-------------------------------------------------------------------------------

All comments below are about very minor potential issues that you may choose to
address in some way - or ignore - as you see fit. Some were flagged by
automated tools (via https://github.com/larseggert/ietf-reviewtool), so there
will likely be some false positives. There is no need to let me know what you
did with these suggestions.

Section 1.2, paragraph 7
> nchronization among PE devices within a Ethernet Segment redundancy group. T
>                                      ^
Use "an" instead of "a" if the following word starts with a vowel sound, e.g.
"an article", "an hour".

Section 2.2, paragraph 2
>  8.5 of [RFC7432] with the default 3 second timer in step 2: 1. Initial stat
>                                    ^^^^^^^^
When "3-second" is used as a modifier, it is usually spelled with a hyphen.

Section 2.2, paragraph 3
> E1. 4. Timer Start: PE2 starts a 3 second timer to allow the reception of RT
>                                  ^^^^^^^^
When a number forms part of an adjectival compound, use a hyphen.

Section 2.2, paragraph 9
> imer Start: PE2 starts at t=100 a 3 second timer to allow the reception of RT
>                                  ^^^^^^^^
When a number forms part of an adjectival compound, use a hyphen.

Section 3, paragraph 9
> se of the SCT approach presented in this documents encourages the use of lar
>                                    ^^^^
The singular determiner "this" may not agree with the plural noun "documents".
Did you mean "these"?

Section 3, paragraph 20
> r Initiation by PE2: PE2 starts a 3 second timer to allow the reception of RT
>                                  ^^^^^^^^
When a number forms part of an adjectival compound, use a hyphen.

Section 3, paragraph 22
> r Initiation by PE3: PE3 starts a 3 second timer to allow the reception of RT
>                                  ^^^^^^^^
When a number forms part of an adjectival compound, use a hyphen.

Section 4, paragraph 2
> NA is requested to confirm the First Come First Served assignment as follows:
>                                      ^^^^
It seems that a comma is missing.

[Ballot comment]
Thank you for this document. No substantive comments. However, nits throws up the following so please review.

  ** The abstract seems to contain references ([RFC8584]), which it
    shouldn't.  Please replace those with straight textual mentions of the
    documents in question.

  -- The draft header indicates that this document updates RFC8584, but the
    abstract doesn't seem to directly say this.  It does mention RFC8584
    though, so this could be OK.

[Ballot comment]

# Éric Vyncke, INT AD, comments for draft-ietf-bess-evpn-fast-df-recovery-09

Thank you for the work put into this document.

Please find below some non-blocking COMMENT points (but replies would be appreciated even if only for my own education), and some nits.

Special thanks to Matthew Bocci for the shepherd's detailed write-up including the WG consensus and the justification of the intended status.

Other thanks to Dave Thaler, the Internet directorate reviewer, and to Toerless Eckert, the IoT directorate reviewer, please consider their reviews as if they were mine:
https://datatracker.ietf.org/doc/review-ietf-bess-evpn-fast-df-recovery-09-intdir-telechat-thaler-2024-08-13/ (I haven't read any public reaction of the authors)
https://datatracker.ietf.org/doc/review-ietf-bess-evpn-fast-df-recovery-09-iotdir-telechat-eckert-2024-08-14/ (I haven't read any public reaction of the authors)

I hope that this review helps to improve the document,

Regards,

-éric

# COMMENTS (non-blocking)

## Section 1.3

PE, DF, HRW acronym are already expanded before ;-)

Suggest defining "redundancy group".

## Section 2

`add a skew (default = -10ms)` while this is valid, isn't it a little weird to add a negative value ?

Should "service carving" be explained/defined ? Perhaps via a reference to another RFC ?

## Section 2.1

`Era 0 is assumed as of the writing of this document` does not age well, strongly suggesting to use "Era 0 is assumed in this specification".

# NITS (non-blocking / cosmetic)

s/Layer2/layer-2/
s/Layer 2/layer-2/ when used as an adjective.
"i.e." should always be followed by a comma.
s/insterted/inserted/ suggest using a spell checker ;-)

[Ballot comment]
# Internet AD comments for draft-ietf-bess-evpn-fast-df-recovery-09
CC @ekline

* comment syntax:
  - https://github.com/mnot/ietf-comments/blob/main/format.md

* "Handling Ballot Positions":
  - https://ietf.org/about/groups/iesg/statements/handling-ballot-positions/

## Comments

### S2

* Where is there operational guidance to PE implementors that "recovery"
  activity SHOULD NOT be initiated until after the configured time
  synchronization operations (e.g. NTP) have occurred?

  I didn't see anything in 7432 nor in 8584, but I might not be looking in
  the right places or for the right keywords.

[Ballot comment]
There are some typos still, but not a ton. 

I'm far from a routing expert, but this draft appeared to me to be clear and understandable.

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

IANA has completed its review of draft-ietf-bess-evpn-fast-df-recovery-09. If any part of this review is inaccurate, please let us know.

IANA understands that, upon approval of this document, there are two actions which we must complete.

First, in the EVPN Extended Community Sub-Types registry in the Border Gateway Protocol (BGP) Extended Communities registry group located at:

https://www.iana.org/assignments/bgp-extended-communities/

the existing early registration will be made permanent:

Sub-type Value: 0x0F
Name: Service Carving Timestamp
Reference: [ RFC-to-be ]
Date: [ TBD-at-Registration ]

Second, in the DF Election Capabilities also in the Border Gateway Protocol (BGP) Extended Communities registry group located at:

https://www.iana.org/assignments/bgp-extended-communities/

a single new registration will be made as follows:

Bit: 3
Name: Time Synchronization
Reference: [ RFC-to-be ]
Date: [ TBD-at-Registration ]

We understand that these are the only actions 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,

David Dong
IANA Services Sr. Specialist

The following Last Call announcement was sent out (ends 2024-07-31):

From: The IESG
To: IETF-Announce
CC: bess-chairs@ietf.org, bess@ietf.org, draft-ietf-bess-evpn-fast-df-recovery@ietf.org, gunter@vandevelde.cc, matthew.bocci@nokia.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Fast Recovery for EVPN Designated Forwarder Election) to Proposed Standard


The IESG has received a request from the BGP Enabled ServiceS WG (bess) to
consider the following document: - 'Fast Recovery for EVPN Designated
Forwarder Election'
  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 2024-07-31. 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


  The Ethernet Virtual Private Network (EVPN) solution provides
  Designated Forwarder (DF) election procedures for multihomed Ethernet
  Segments.  These procedures have been enhanced further by applying
  Highest Random Weight (HRW) algorithm for Designated Forwarder
  election in order to avoid unnecessary DF status changes upon a
  failure.  This document improves these procedures by providing a fast
  Designated Forwarder election upon recovery of the failed link or
  node associated with the multihomed Ethernet Segment.  This document
  updates Section 2.1 of [RFC8584] by optionally introducing delays
  between some of the events therein.

  The solution is independent of the number of EVPN Instances (EVIs)
  associated with that Ethernet Segment and it is performed via a
  simple signaling between the recovered node and each of the other
  nodes in the multihoming group.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-bess-evpn-fast-df-recovery/



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

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?

There is consensus among the core active participants in the WG to publish this draft. 

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

None indicated.

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize 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.)

None indicated.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?

BESS has a policy of requiring at least one implementation for standards track protocol drafts before proceeding.
There is at least one known implementation which has been declared on the BESS list during an implementation poll.


## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.

BESS typically cross-reviews documents that make significant extensions to BGP with the IDR working group.
This draft only requests a new extended community from the EVPN extended community sub-types and a new EVPN DF Election Capability  (EVPN
being being owned by BESS), and therefore no further review was considered necessary. 

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

N/A

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] 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 [RFC 8342][5]?

N/A

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

N/A

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?

I have reviewed the document and provided the authors with comments, which have been addressed.
As a part of this review, I noted that I believed the document updated RFC8584. Text describing this, and which parts are updated,
was subsequently added to the draft. Since this change occurred after working group last call, the working group was polled to see if
anyone believed that there would be interoperability issues between a 'legacy' implementation of RFC8584 and a newer implementation that
also conformed to this draft. The consensus was that the update would not cause interoperability issues.

The document is clear and is needed. It describes implemented protocol extensions. I believe it is ready to be reviewed by the AD.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

No lists of common issues identified.

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

Standards Track. This is appropriate as the draft describes protocol extensions and requests a new extended community and DF election capability be allocated from an IANA registry.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.

Yes. There are no IPR disclosures. All authors and contributors have confirmed that they are not aware of any IPR that has not already been declared.

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.

The draft has 4 authors listed, and they are all known to be active contributors to this technology.

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

No significant nits.

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

References are all classified as Normative, but this seems reasonable in this case.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?

All normative references are to published RFCs.

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

No.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?

No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

No.

20. 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 aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

No issues identified.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

None required.

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://trac.ietf.org/trac/ops/wiki/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://trac.ietf.org/trac/iesg/wiki/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?

There is consensus among the core active participants in the WG to publish this draft. 

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

None indicated.

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize 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.)

None indicated.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?

BESS has a policy of requiring at least one implementation for standards track protocol drafts before proceeding.
There is at least one known implementation which has been declared on the BESS list during an implementation poll.


## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.

BESS typically cross-reviews documents that make significant extensions to BGP with the IDR working group.
This draft only requests a new extended community from the EVPN extended community sub-types and a new EVPN DF Election Capability  (EVPN
being being owned by BESS), and therefore no further review was considered necessary. 

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

N/A

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] 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 [RFC 8342][5]?

N/A

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

N/A

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?

I have reviewed the document and provided the authors with comments, which have been addressed.
As a part of this review, I noted that I believed the document updated RFC8584. Text describing this, and which parts are updated,
was subsequently added to the draft. Since this change occurred after working group last call, the working group was polled to see if
anyone believed that there would be interoperability issues between a 'legacy' implementation of RFC8584 and a newer implementation that
also conformed to this draft. The consensus was that the update would not cause interoperability issues.

The document is clear and is needed. It describes implemented protocol extensions. I believe it is ready to be reviewed by the AD.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

No lists of common issues identified.

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

Standards Track. This is appropriate as the draft describes protocol extensions and requests a new extended community and DF election capability be allocated from an IANA registry.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.

Yes. There are no IPR disclosures. All authors and contributors have confirmed that they are not aware of any IPR that has not already been declared.

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.

The draft has 4 authors listed, and they are all known to be active contributors to this technology.

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

No significant nits.

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

References are all classified as Normative, but this seems reasonable in this case.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?

All normative references are to published RFCs.

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

No.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?

No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

No.

20. 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 aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

No issues identified.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

None required.

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://trac.ietf.org/trac/ops/wiki/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://trac.ietf.org/trac/iesg/wiki/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?

There is consensus among the core active participants in the WG to publish this draft. 

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

None indicated.

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize 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.)

None indicated.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?

BESS has a policy of requiring at least one implementation for standards track protocol drafts before proceeding.
There is at least one known implementation which has been declared on the BESS list during an implementation poll.


## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.

BESS typically cross-reviews documents that make significant extensions to BGP with the IDR working group.
This draft only requests a new extended community from the EVPN extended community sub-types and a new EVPN DF Election Capability  (EVPN
being being owned by BESS), and therefore no further review was considered necessary. 

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

N/A

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] 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 [RFC 8342][5]?

N/A

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

N/A

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?

I have reviewed the document and provided the authors with comments, which have been addressed. The document is clear and is needed. It describes implemented protocol extensions. I believe it is ready to be reviewed by the AD.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

No lists of common issues identified.

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

Standards Track. This is appropriate as the draft describes protocol extensions and requests a new extended community and DF election capability be allocated from an IANA registry.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.

Yes. There are no IPR disclosures. All authors and contributors have confirmed that they are not aware of any IPR that has not already been declared.

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.

The draft has 4 authors listed, and they are all known to be active contributors to this technology.

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

No significant nits.

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

References are all classified as Normative, but this seems reasonable in this case.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?

All normative references are to published RFCs.

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

No.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?

No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

No.

20. 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 aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

No issues identified.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

None required.

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://trac.ietf.org/trac/ops/wiki/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://trac.ietf.org/trac/iesg/wiki/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

Request for posting confirmation emailed to previous authors: Ali Sajassi , Dhananjaya Rao , Gaurav Badoni , John Drake , Jorge Rabadan , Patrice Brissette , bess-chairs@ietf.org