Re: [Lsr] WG Last Call for draft-ietf-lsr-flex-algo

["Les Ginsberg (ginsberg)" <[e-mail]>]

Tony –

As an author of both RFC 8570 and I-D.ietf-isis-te-app, I am not sure why you are confused – nor why you got misdirected to code point 33.

RFC 8570 (and its predecessor RFC 7810) define:

34           Min/Max Unidirectional Link Delay

This sub-TLV contains two values:

“Min Delay:  This 24-bit field carries the minimum measured link delay
      value (in microseconds) over a configurable interval, encoded as
      an integer value.

   Max Delay:  This 24-bit field carries the maximum measured link delay
      value (in microseconds) over a configurable interval, encoded as
      an integer value.”

It seems clear to me that the flex-draft is referring to Min Unidirectional Link Delay in codepoint 34.

I agree it is important to be unambiguous in specifications, but I think Peter has been very clear.
Please explain how you managed to end up at code point 33??

   Les



From: Lsr <[e-mail]> On Behalf Of [e-mail]
Sent: Tuesday, August 18, 2020 7:44 AM
To: Peter Psenak (ppsenak) <[e-mail]>
Cc: [e-mail]; [e-mail]; Christian Hopps <[e-mail]>; Acee Lindem (acee) <[e-mail]>; [e-mail]
Subject: Re: [Lsr] WG Last Call for draft-ietf-lsr-flex-algo


Hi Peter,



section 5.1 of the draft-ietf-lsr-flex-algo says:

Min Unidirectional Link Delay as defined in [I-D.ietf-isis-te-app].

We explicitly say "Min Unidirectional Link Delay", so this cannot be mixed with other delay values (max, average).


The problem is that that does not exactly match “Unidirectional Link Delay” or “Min/Max Unidirectional Link Delay”, leading to the ambiguity. Without a clear match, you leave things open to people guessing. Now, it’s a metriic, so of course, you always want to take the min.  So type 33 seems like a better match.




section 7.3. of ietf-isis-te-app says:

Type   Description                          Encoding
                                           Reference
---------------------------------------------------------
34      Min/Max Unidirectional Link Delay    RFC8570


And it also says:


33      Unidirectional Link Delay            RFC8570<https://tools.ietf.org/html/rfc8570>


This does not help.



So, IMHO what we have now is correct and sufficient, but I have no issue adding the text you proposed below.


What you have now is ambiguous. We have a responsibility, as writers of specifications, to be precise and clear.  We are not there yet.



BTW, before I posted 09 version of flex-algo draft, I asked if you were fine with just referencing ietf-isis-te-app in 5.1. I thought you were, as you did not indicate otherwise.


My bad, I should have pressed the issue.



Anyway, I consider this as a pure editorial issue and hopefully not something that would cause you to object the WG LC of the flex-algo draft.


I’m sorry, I think that this is trivially resolved, but important clarification.

You also have an author’s email that is bouncing, so at least one more spin is required.

Sorry,
Tony