[Detnet] AD Review of draft-ietf-detnet-pof-04

[Roman Danyliw <[e-mail]>]

Hi!

I performed an AD review on draft-ietf-detnet-pof-04 to help load balance the IESG PubReq queue.  Thanks for this document.  I have the following feedback, largely to improve clarity.

Please review and respond to Henning Rogge's review at https://datatracker.ietf.org/doc/review-ietf-detnet-pof-04-rtgdir-early-rogge-2023-10-23/ -- thanks Henning!
In particular, please review his hypothetical case of seq= 10, 5, 7 and 9 per the algorithm in Section 4.3.

** Section 1.
   3 errors in-a-row is a usual error threshold and
   can cause the application to stop (e.g., to go to a fail-safe state)

What is the basis for assessment that 3 is a common error threshold in applications?

** Section 4.3. I am unsure of the framing assumed with of Detnet as it applies here.  Is there obvious basic assumption around the seq_num coming from a layer 2 or 3 protocol (e.g., it has one?  Which one would you choose?)  Please add text similar to Section 1 of draft-ietf-detnet-mpls-over-ip-preof-07 without the reference to timestamps:

   In general, the use of PREOF functions require sequencing information
   to be included in the packets of a DetNet compound flow.  This can be
   done by adding a sequence number or time stamp as part of DetNet
   encapsulation.  Sequencing information is typically added once, at or
   close to the source.

** Section 4.3.
   Note: the difference of sequence number in consecutive packets is
   bounded due to the history window of the Elimination function before
   the POF.  Therefore "<=" can be evaluated despite of the circular
   sequence number space.

As far as I can tell find, the “history window of the elimination function” is not defined.

** Section 4.3
   *  "POFMaxDelay", which cannot be smaller than the delay difference
      of the paths used by the flow.

Is “delay difference” than the worst-case value for the end-to-end latency?

** Section 4.3.  Editorial.  Per Figure 3, are “fastest” and “slowest” the right adjectives to use for a time duration?
-- “fastest path delay” to “shortest path delay”?
-- “slowest path delay” to “longest path delay”?

** Section 4.5.  Recommend repeating what was already said in Section 4.3, “Design of these parameters is out-of-scope in this document.”

Regards,
Roman