Re: [mpls] working group last call on draft-ietf-mpls-spring-entropy-label

If I look at section 4, the key piece of information is the RLD which
is the subject of other drafts. Given the RLD, how it is decided
to distribute the ELIs within the stack is purely a local matter.

5.1 is the trivial case of 4 for a large RLD, and for shorter RLD
is a matter for the imposing LSR to balance reduction in
ECMP against LS size (which may be a limit for that LSR anyway).
Either way unless you use some sort of phone a friend scheme*
(which you may need as the label stack grows beyond the capability of
the edge nodes) this is a local matter.

5.2 is the other trivial case of 4, which again is a local matter.

5.3 and 5.3.1 require hardware changes, but optimises the stack
size, which is an oft quoted issue in MPLS systems, particularly
PWs. As such it is not a local matter, but if you knew that strategic
nodes had that capability it would become a local matter.

Incidentally there is a need for something of the form of 5.3
in that an LSR pushing further labels may need to look at the existing
stack, retrieve the EL and add its own ELI/ELs. There perhaps
ought to be text describing this action, but once you have this
capability, surely 5.3 becomes a viable general solution.

Also a 5.3 like solution may be needed to overcome the
ingress node imposition limitations in cases where phone-a-friend
is not available.

5.4 is as the document notes really a version of 4.

There is so much that is a local matter that I am not sure the text
should go beyond describing the issues and leaving the decision
to the imposing LSR s/w team.

- Stewart

*As I recall that there is IPR on at least one phone-a-friend scheme

On 26/04/2016 06:03, Loa Andersson wrote:
> Greg,
>
> (talking about the SHOULDs in Section 4 only)
>
> I think what George (and Stewart) says is that since the document does
> not use any MUST, SHALL or REQUIRED, it makes sense to publish it as an
> Informational RFC.
>
> However, it does not work to turn that argument around and say that an
> Informational RFC can't use the normative language, it was doen for 
> example in RFC 7412.
>
> I think we should change it to Informational, but there is no need to
> do anything to the SHOULDs in section 4.
>
> /Loa
>
> On 2016-04-26 03:19, Gregory Mirsky wrote:
>> Hi George, et. al,
>>
>> I’ve found several occurrences, three actually, of SHOULD being used in
>> Section 4.
>>
>> And I agree with Stewart that application of <ELI, EL> is the local
>> decision and, at most, this work can be published as Informational.
>>
>> One comment, suggestion:
>>
>> ·the sample algorithm in Section 4 suggests that the same <ELI,EL> tuple
>> been used multiple times whereas it may be advantageous to generalize
>> and point that the different entropy label value may be used by
>> referring to the tuple as <ELI, ELn>
>>
>> Regards,
>>
>>          Greg
>>
>> *From:*mpls [mailto:mpls-bounces@ietf.org] *On Behalf Of *George Swallow
>> *Sent:* Monday, April 25, 2016 10:57 AM
>> *To:* Stewart Bryant
>> *Cc:* draft-ietf-mpls-spring-entropy-label@tools.ietf.org;
>> mpls@ietf.org; mpls-chairs@ietf.org
>> *Subject:* Re: [mpls] working group last call on
>> draft-ietf-mpls-spring-entropy-label
>>
>> Stewart -
>>
>> On Mon, Apr 25, 2016 at 9:58 AM, Stewart Bryant
>> <stewart.bryant@gmail.com <mailto:stewart.bryant@gmail.com>> wrote:
>>
>> I support this becoming a WG doc and thereby comming under WG
>> control.
>>
>> The document is a WG doc.   We are now in WG last call.
>>
>>     However I am not sure about the dismissal of the option to reuse
>>     the ELI+EL. This clutters the stack less than the proposed option.
>>
>>     Also I wonder why this is standards track?
>>
>> A reasonable question, particularly since there are no MUSTs, SHALLs or
>> REQUIREDs.  Will discuss with my Co-Chairs and ADs.
>>
>>     Surely any equipment that understands the ELI can do this and thus
>>     this is just an informal description of the problem and a solution.
>>
>>     Stewart
>>
>>
>>
>>     On 23/04/2016 08:53, Loa Andersson wrote:
>>
>>     Working Group,
>>
>>     This is to initiate a two week working group last call on
>>     draft-ietf-mpls-spring-entropy-label.
>>
>>     Please send your comments to the mpls wg mailing list (mpls@ietf.org
>>     <mailto:mpls@ietf.org>).
>>
>>     There are no IPR disclosures against this document.
>>
>>     All the authors and contributors (with one exception) have stated on
>>     the working group mailing list that they are not aware of any other
>>     IPRs that relates to this draft.
>>
>>     This working group last call ends May 12, 2016.
>>
>>
>>     /Loa
>>     for the MPLS wg chairs
>>
>>
>>
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