Eric, Stewart, wg,
Wouldn't just a few words in the draft saying something along the lines
"This document should not be interpreted in such a way that the ECMP
behavior is limited to rely on EL only."
Go a long way to clarify Stewart's concerns?
/Loa
On 2018-05-02 16:52, Eric Gray wrote:
Stewart, et al,
Loa just pointed out that I made a typo in the original
mail below. In the second paragraph, I meant to say:
“Explicitly limiting ECMP behavior to …”
--
Eric
*From:*mpls [mailto:[email protected]] *On Behalf Of *Eric Gray
*Sent:* Wednesday, May 02, 2018 10:28 AM
*To:* Stewart Bryant <[email protected]>; Andrew G. Malis
<[email protected]>; Loa Andersson <[email protected]>
*Cc:* [email protected]; [email protected]; [email protected];
[email protected]
*Subject:* Re: [mpls] [spring] should
draft-ietf-mpls-spring-entropy-label be published as a RFC on the
standards track?
Stewart,
At least one view of the purpose of an Entropy label is
that it _/adds/_ entropy to the process of path selection.
Explicitly limiting EL behavior to rely exclusively on
use of the entropy label would also explicitly _/limit/_ the total
entropy to whatever the implementation that provided the entropy label
was implemented to treat as _/sufficient/_ among all paths in the ECMP
gestalt, possibly including branches that implementation might not know
about.
I doubt very much that many of the problems you refer
to would have arisen if folks generally felt that the entropy label – by
itself – provides sufficient entropy.
It might make sense to impose this restriction –
optionally – when a deployment occurs in which any particular
pathological behavior might be expected to occur.
In that case, it might be very important to ensure that
the limited approaches available for maximizing efficient load
distribution via explicit and exclusive use of the entropy label are
acceptable to a reasonably diverse set of implementers, as support for
at least one of those approaches would then become a mandatory part of
every standard implementation.
Even so, I don’t believe it is a good idea to restrict
implementations from using other approaches in every case.
The simplest example possible (where doing so is a big
problem) is one where the entropy labels provided have N possible
values and there are M possible paths, where M>N. In any scenario where
this occurs, M-N paths simply will not be used.
--
Eric
*From:*mpls [mailto:[email protected]] *On Behalf Of *Stewart Bryant
*Sent:* Wednesday, May 02, 2018 9:52 AM
*To:* Andrew G. Malis <[email protected] <mailto:[email protected]>>;
Loa Andersson <[email protected] <mailto:[email protected]>>
*Cc:* [email protected] <mailto:[email protected]>; [email protected]
<mailto:[email protected]>; [email protected] <mailto:[email protected]>;
[email protected]
<mailto:[email protected]>
*Subject:* Re: [mpls] [spring] should
draft-ietf-mpls-spring-entropy-label be published as a RFC on the
standards track?
Be careful.
There is text in the draft that talks about ECMP behaviour in different
parts of the path, which implies an expectation that the EL is the sole
source of entropy. If we make this ST then we will be implicitly
standardizing that behaviour. Now as it happens, I thing we need to
update the EL behaviour to make it the sole source of entropy, because
that solves a number of problems, particularly in network
instrumentation, but we need to do that explicitly and not as an
artefact of this draft.
So the way I see it, either this draft is published as informational, or
it is published as ST without any text that implies that the EL is the
sole source of entropy, or we harden the EL behaviour (which I think we
need to do) and this draft is published with a normative reference to an
RFC that specifies the stricter EL behaviour.
- Stewart
On 02/05/2018 14:01, Andrew G. Malis wrote:
Loa,
There’s plenty of RFC 2119 language in the draft, so I support
making this standards track.
Cheers,
Andy
On Wed, May 2, 2018 at 3:44 AM, Loa Andersson <[email protected]
<mailto:[email protected]>> wrote:
Working Group,
February 1st the MPLS working Group requested that draft-ietf-mpls-
spring-entropy-label should be published as an Informational RFC.
During the RTG Directorate and AD reviews the question whether the
document should instead be published as a RFC on the Standards Track
has been raised.
The decision to make the document Informational was taken "a
long time
ago", based on discussions between the authors and involving the
document shepherd, on the wg mailing list. At that point it we were
convinced that the document should be progressed as an Informational
document.
It turns out that there has been such changes to the document
that we
now would like to request input from the working group if we
should make
the document a Standards Track RFC.
Daniele's RTG Directorate review can be found at at:
https://datatracker.ietf.org/doc/review-ietf-mpls-spring-entropy-label-08-rtgdir-lc-ceccarelli-2018-02-21/
All the issues, with the exception whether it should be
Informational
or Standards track, has been resolved as part AD review.
If the document is progressed as a Standard Tracks document then we
also need to answer the question whether this is an update RFC 6790.
This mail starts a one week poll (ending May 9) to see if we have
support to make the document a Standards Track document. If you
support
placing it on the Standards Track also consider if it is an
update to
RFC 6790.
Please send your comments to the MPLS wg mailing list (
[email protected] <mailto:[email protected]> ).
/Loa
for the mpls wf co-chairs
PS
I'm copying the spring working group on this mail.
--
Loa Andersson email: [email protected]
<mailto:[email protected]>
Senior MPLS Expert
Bronze Dragon Consulting phone: +46 739 81 21 64
_______________________________________________
mpls mailing list
[email protected] <mailto:[email protected]>
https://www.ietf.org/mailman/listinfo/mpls
_______________________________________________
spring mailing list
[email protected] <mailto:[email protected]>
https://www.ietf.org/mailman/listinfo/spring
--
Loa Andersson email: [email protected]
Senior MPLS Expert
Bronze Dragon Consulting phone: +46 739 81 21 64
_______________________________________________
spring mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/spring
