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 08:02 UTC

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From: "Andrew G. Malis" <agmalis@gmail.com>
Date: Tue, 21 Jul 2015 10:02:36 +0200
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To: "S. Davari" <davarish@yahoo.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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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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