Re: [mpls] draft-fang-mpls-label-forwarding-no-swap - how much does it really save?

"Andrew G. Malis" <agmalis@gmail.com> Tue, 21 July 2015 08:29 UTC

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From: "Andrew G. Malis" <agmalis@gmail.com>
Date: Tue, 21 Jul 2015 10:29:01 +0200
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To: Alexander Vainshtein <Alexander.Vainshtein@ecitele.com>
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Subject: Re: [mpls] draft-fang-mpls-label-forwarding-no-swap - how much does it really save?
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Sasha,

That's why I said "if it goes forward".

Cheers,
Andy

On Tue, Jul 21, 2015 at 10:26 AM, Alexander Vainshtein <
Alexander.Vainshtein@ecitele.com> wrote:

>  Andy, Shahram and all,
>
>
>
> I may have missed something, but I do not understand why this draft is
> needed even as an Informational since, as Eric has noticed, it describes a
> local optimization trick.
>
>
>
>
>
> Regards,
>
> Sasha
>
>
>
> Office: +972-39266302
>
> Cell:      +972-549266302
>
> Email:   Alexander.Vainshtein@ecitele.com
>
>
>
> *From:* mpls [mailto:mpls-bounces@ietf.org] *On Behalf Of *Andrew G. Malis
> *Sent:* Tuesday, July 21, 2015 11:03 AM
> *To:* S. Davari
> *Cc:* mpls@ietf.org
> *Subject:* Re: [mpls] draft-fang-mpls-label-forwarding-no-swap - how much
> does it really save?
>
>
>
> As there are no architectural or protocol changes or IANA considerations,
> this draft should be informational if it goes forward (it currently says
> "standards track").
>
>
>
> Cheers,
>
> Andy
>
>
>
>
>
> On Mon, Jul 20, 2015 at 8:52 PM, S. Davari <davarish@yahoo.com> wrote:
>
> Eric
>
> I agree no standard change is required since this is a local optimization
> issue.
>
> Regards,
> Shahram
>
>
> > On Jul 20, 2015, at 11:43 AM, Eric C Rosen <erosen@juniper.net> wrote:
> >
> >> On 7/20/2015 2:07 PM, Shahram Davari wrote:
> >> The new swapped labels (The outgoing  label that replaces the
> >> incoming label) need to be stored in a table. Using this draft
> >> reduces the number of swapped labels that needs to be stored,
> >> regardless of  implementation. Don't you agree?
> >
> > No.  If you notice that the incoming label needs to be 'replaced' by an
> outgoing label of the same value, you could just make the rewrite string
> shorter, so it won't overwrite the top label on the stack.  This seems to
> be what the draft suggests, but it could be done as an optimization for the
> particular case where the incoming and outgoing labels have the same
> value.  You could do this today, as a local implementation optimization.
> There doesn't seem to be any interop issue or any change to the data plane
> semantics.
> >
> >> It also reduces the configuration and management of the new swapped
> labels.
> >
> > We're not discussing whether there are any advantages to the use of
> domain-wide labels.  We're discussing whether the use of domain-wide labels
> requires a change in the forwarding plane architecture.  I just don't see
> that it does.
> >
> > _______________________________________________
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