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 <lsr-boun...@ietf.org> On Behalf Of tony...@tony.li
Sent: Tuesday, August 18, 2020 7:44 AM
To: Peter Psenak (ppsenak) <ppse...@cisco.com>
Cc: lsr@ietf.org; lsr-...@ietf.org; Christian Hopps <cho...@chopps.org>; Acee
Lindem (acee) <a...@cisco.com>; draft-ietf-lsr-flex-algo....@ietf.org
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
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