Tony/Robert –
Whatever clarification Peter may choose to make would be fine – but I do
question your casual ignoring of adjectives. 😊
There are three values being advertised:
33 - Unidirectional Link Delay
34 – Min/Max Unidirectional Link Delay
Meaning two values are advertised in this codepoint:
Min Unidirectional Link Delay
Max Unidirectional Link Delay
Now, the flex algo draft states: Min Unidirectional Link Delay
If you want to argue that “Min Unidirectional Link Delay” != “Min/Max
Unidirectional Link Delay” – I think you are pedantically correct.
But how that leads you to simply truncate “Min” and conclude that this is
really “Unidirectional Link Delay” is a leap that I cannot follow.
Perhaps you don’t really like the fact that RFC 8570 encoding combined Min/Max
in a single codepoint – but that ship sailed years ago.
Given that RFC 8570 is very clear in showing that the encoding includes:
<snip>
0 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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| RESERVED | Min Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED | Max Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
<end snip>
my ability to see your POV is somewhat limited.
Perhaps you could own that a more careful reading is possible?
Les
From: Lsr <[email protected]> On Behalf Of [email protected]
Sent: Tuesday, August 18, 2020 10:03 AM
To: Robert Raszuk <[email protected]>
Cc: Christian Hopps <[email protected]>; [email protected];
Les Ginsberg (ginsberg) <[email protected]>; [email protected];
[email protected]; Acee Lindem (acee) <[email protected]>; Peter Psenak (ppsenak)
<[email protected]>
Subject: Re: [Lsr] WG Last Call for draft-ietf-lsr-flex-algo
Robert,
Thank you, exactly.
We just need a clarification of the document. I don’t understand why this is
such a big deal.
Tony
On Aug 18, 2020, at 9:22 AM, Robert Raszuk
<[email protected]<mailto:[email protected]>> wrote:
Les,
I think this is not very obvious as Tony is pointing out.
See RFC 8570 says:
Type Description
----------------------------------------------------
33 Unidirectional Link Delay
34 Min/Max Unidirectional Link Delay
That means that is someone implementing it reads text in this draft literally
(meaning Minimum value of Unidirectional Link Delay) it may pick minimum value
from ULD type 33 :)
If you want to be precise this draft may say minimum value of Min/Max
Unidirectional Link Delay (34) and be done.
That's all.
Cheers,
R.
On Tue, Aug 18, 2020 at 6:04 PM Les Ginsberg (ginsberg)
<[email protected]<mailto:[email protected]>> wrote:
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 <[email protected]<mailto:[email protected]>> On Behalf Of
[email protected]<mailto:[email protected]>
Sent: Tuesday, August 18, 2020 7:44 AM
To: Peter Psenak (ppsenak) <[email protected]<mailto:[email protected]>>
Cc: [email protected]<mailto:[email protected]>;
[email protected]<mailto:[email protected]>; Christian Hopps
<[email protected]<mailto:[email protected]>>; Acee Lindem (acee)
<[email protected]<mailto:[email protected]>>;
[email protected]<mailto:[email protected]>
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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