Olivier,
On 20/08/2020 16:25, [email protected] wrote:
Peter,
Le 20/08/2020 à 14:12, Peter Psenak a écrit :
Hi Olivier,
On 20/08/2020 13:58, [email protected] wrote:
Hi Peter,
Thank for the new version.
Le 19/08/2020 à 14:00, Peter Psenak a écrit :
Olivier,
[ ... ]
So, to speed up the deployment, I would prefer a reference to a
delay value that could be advertise by means of RFC7471, RFC8570
and/or TE-App draft. It is then up to the operator to ensure the
coherency of what it is announced in its network by the different
routers.
I know you don't like the app specific link advertisement, but I'm
afraid what you ask for is absolutely wrong.
We defined the ASLA encoding to address a real problems for
advertising the link attributes. We allow the link attributes to be
advertised in both legacy and ASLA advertisement for legacy
application (RSVP-TE, SRTE) to address the backward compatibility.
Flex-algo is a new application, there is absolutely no need to use
the legacy advertisement. Doing so would just extend the problem to
the flex-algo application.
Regarding the new version you provided, new section 5.1 (for IS-IS)
and section 5.2 (for OSPF) mention respectively RFC 8570 and RFC 7471
for the definition of Min delay and TE metric which is fine for me.
But, they also made reference to draft isis-te-app, respectively
ospf-te-link-attr-reuse to encode these value.
that's what people were asking for. And it is right because we are
mandating the usage of ALSA encoding for any flex-algo related link
attributes.
Here, it is confusing.
I don't see how much more clear we can make it.
Indeed, RFC 8570 and RFC 7471 also define the way to encode TE metric
and Min delay.
you have to distinguish between two things:
a) where Min delay and TE metric were defined - RFC 8570 and RFC 7471
b) how we encode it for flex-algo - isis-te-app,
ospf-te-link-attr-reuse
What I'm suggesting, is a clear reference to the RFC for TE metric
and Min delay definition as well as the encoding (especially for the
delay) while leaving open the door to how the router acquire these
values: legacy a.k.a. RFC 8570 & 7471 or new draft a.k.a
draft-isis-te-app & draft-ospf-link-attr-reuse.
no. This will not be done. We only allow ASLA advertisement for these
metrics and other link attributes that are used for flex-algo. It is
done for a reason and I have already explained that.
OK. Reading section 11 which clarify how metrics are convey, let me
suggest to make a reference to section 11 in section 5.1 and 5.2 instead
of reference to drafts.
what is the problem with using the reference to isis-te-app,
ospf-te-link-attr-reuse in 5.1 and 5.2?
In fact, in section 17.1.2, you mention only reference to RFC 8570 &
RFC7471 for the IANA definition which is fine for me.
because in registry, we are defining a metric type, not how we are
going to advertise it for the link.
OK.
I would suggest the same wording for section 5.1. and 5.2 leaving
operator free about how it collect the values from the neighbour
routers: legacy or new method.
please stop trying to make use of legacy RSVP-TE link advertisements
for flex-algo - it will not be allowed.
This raise to me a simple question: Is it possible to use 2 different
Flex Algo with delay metric, one for App A and another one for App B ?
sure
if yes, how can we link metrics advertise in ALSA A from metrics
advertise in ALSA B ? The draft mention only one bit for Flex-Algo.
there is only single ASLA flex-algo delay metric advertisement per link,
similar to only single RSVP-TE delay metric per link.
Advertisement is done per application type, flex-algo being one of them,
not per each instance of the application (e.g. flex-algo number).
Regards,
Olivier
PS. I note a duplicate paragraph in section 12: "When computing the path
for a given Flex-Algorithm, the metric-type that is part of the
Flex-Algorithm definition (Section 5) MUST be used."
I don't see it. I see one talking about metric, the other one about the
calculation type.
thanks,
Peter
thanks,
Peter
Regards
Olivier
PS. We have a pre-alpha implementation of flex algo using the legacy
metrics and I know that recent IOS-XR provided similar implementation
of flex algo based on legacy metrics.
regards,
Peter
Regards
Olivier
Le 18/08/2020 à 19:02, [email protected] a écrit :
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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Ce message et ses pieces jointes peuvent contenir des informations
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a l'expediteur et le detruire ainsi que les pieces jointes. Les
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This message and its attachments may contain confidential or
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Thank you.
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Orange logo <http://www.orange.com>
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Orange Expert, Future Networks
Open Source Referent
Orange/IMT/OLN/WTC/IEE/iTeQ
fixe : +33 2 96 07 28 80
mobile : +33 6 82 90 37 85
[email protected] <mailto:[email protected]>
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confidentielles ou privilegiees et ne doivent donc
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message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages
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Orange decline toute responsabilite si ce message a ete altere, deforme ou
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