Re: [mpls] Solicit Opinions on Definition of MPLS Global Label

Aren't you really discussing label spaces....

You have well known labels (reserved, or administered by the "designers"), and the other label spaces have properties based upon a combination of scope and "who" administers them...

Cheers
Dave

-----Original Message-----
From: mpls [mailto:mpls-bounces@ietf.org] On Behalf Of Loa Andersson
Sent: Thursday, November 05, 2015 10:23 AM
To: Alexander Vainshtein; bruno.decraene@orange.com; Lizhenbin; Nobo Akiya (nobo) (nobo@cisco.com)
Cc: mpls@ietf.org
Subject: Re: [mpls] Solicit Opinions on Definition of MPLS Global Label

Working Group,

We a long-standing usage (though not always well-documented) of some of our labels

global labels - that is a label that have the same meaning for any mpls device, as long as it understand the device understands it, where ever that device is found.
As far as I'm concerned there are only one set of such "global labels", we have chosen to call those Special Purpose Labels.

context specific labels - that are sets of labels that are know within certain context, this context could be any number of things, e.g. a domain.

link local labels - labels that are know over a link between two LSRs, whether the LSRs are adjacent or not.

I don't think we want to move away from this long-standing usage.

/Loa

On 2015-11-05 00:15, Alexander Vainshtein wrote:
> Hi all,
>
> I concur with Bruno: SR does not need global labels.
>
> And, as Nobo has explained
> <http://www.ietf.org/mail-archive/web/mpls/current/msg12640.html> more 
> than 1 year ago, neither does SFC.
>
> Since you solicit opinions, mine is that /global labels are not needed 
> anywhere / because, quoting from RFC 1925 
> <https://tools.ietf.org/html/rfc1925>, "/In protocol design, 
> perfection has been reached not when there is nothing left to add, but 
> when there is nothing left to take away/". Since global labels can 
> always be taken away, any design that uses them would be less than perfectL.
>
> My 2c,
>
> Sasha
>
> Office: +972-39266302
>
> Cell:      +972-549266302
>
> Email:   Alexander.Vainshtein@ecitele.com
>
> *From:*mpls [mailto:mpls-bounces@ietf.org] *On Behalf Of 
> *bruno.decraene@orange.com
> *Sent:* Wednesday, November 04, 2015 8:27 AM
> *To:* Lizhenbin
> *Cc:* mpls@ietf.org
> *Subject:* Re: [mpls] Solicit Opinions on Definition of MPLS Global 
> Label
>
> Hi Robin,
>
> Since I did not get the chance to express my comment during the 
> meeting, I'll do over email.
>
> <spring co-chair hat on>
>
> SPRING/SR:
>
> - is compliant with the MPLS architecture (RFC 3031)
>
>                  - in particular, in the control plane labels are 
> locally allocated and in the forwarding plane, labels (of global
> segments) are SWAPed
>
> - does NOT need global/domain wide label
>
>                  - local segments uses local labels
>
>                  - global segments uses global index + local labels 
> (aka
> SRGB)
>
> - is not requesting the MPLS WG to work on global/domain wide label.
> (i.e. the debate is closed from the SPRING standpoint.). Obviously, 
> the MPLS WG is free to re-open the debate, but this is not a spring thing.
>
> </spring co-chair hat on>
>
> Based on this, some of your slides referring to "SR uses cases" seem a 
> bit misleading. (I can't be more specific since during the meeting, I 
> could see the slides but could not comment, and now I can comment but 
> can't see the slides as they are not online).
>
> Thanks
>
> -- Bruno
>
> *From:*mpls [mailto:mpls-bounces@ietf.org] *On Behalf Of *Lizhenbin
> *Sent:* Wednesday, November 04, 2015 2:27 PM
> *To:* mpls@ietf.org <mailto:mpls@ietf.org>
> *Subject:* [mpls] Solicit Opinions on Definition of MPLS Global Label
>
> Hi MPLSers,
>
> As the development of MPLS technologies, many new label concepts 
> beyond
> RFC3031 are proposed. And in segment routing MPLS label can be
>
> allocated and flooded in the network which means the meaning of the 
> lablel can be understood by all nodes in the network. It is totally 
> different from
>
> the label distribution behavior of LDP, RSVP-TE, and MP-BGP. From my 
> point of view we need not argue if it is global label or global ID. In 
> fact, the
>
> possible persons who read the drafts of protocol extensions for 
> segment routing which incorporate the label allocation may be confused 
> that MPLS WG as
>
> the base of MPLS work seems to have nothing with the work. But the 
> challenge of definition of global label truly exists which has been 
> proposed in the draft
>
> https://www.ietf.org/id/draft-li-mpls-global-label-usecases-03.txt. 
> Hope you can refer to Section 4 of the draft.
>
> The debates on MPLS global label have lasted for a long time. The 
> opinions can be classified as following:
>
> Opinion 1: Segment Routing has nothing with global label and please do 
> not make it bother MPLS WG. But it seems a little hard to convince 
> some MPLSers.
>
> Opinion 2: The usecase truly exists. But the concept of global label 
> is too big. It is hard to allocate a label which is unique spanning 
> multiple domains or
>
> as IP address which is unique all over world since it is not a 
> scalable way or it is hard to achieve the goal. Then maybe it is a 
> better way to narrow the
>
> scope to rename the global label as Domain-wide label, Network-wide 
> label, etc.
>
> Opinion 3: The global label can be kept to cover more label concepts 
> which label behaviors in the control plane and forward plane are 
> different form the
>
> traditional LDP/RSVP-TE/MP-BGP.
>
> Since I could not get more time in my presentation to collect your 
> opinions, if convenient please help feedback your opinion in your 
> mailing list. Hope through
>
> the discussion we can make some consensus.
>
> Best Regards,
>
> Zhenbin(Robin)
>
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