Re: [PWE3] once upon an erratum

[Alexander Vainshtein <[e-mail]>]

Yaakov, Stewart,
Apologies again. But I hope the intention is clear...

Regards,
     Sasha

> -----Original Message-----
> From: Yaakov Stein [mailto:[e-mail]]
> Sent: Wednesday, May 09, 2012 4:11 PM
> To: Alexander Vainshtein; [e-mail]
> Cc: [e-mail]
> Subject: RE: [PWE3] once upon an erratum
> 
> Well, actually it is 5603 ...
> 
> Y(J)S
> 
> -----Original Message-----
> From: [e-mail] [mailto:[e-mail]] On Behalf
> Of Alexander Vainshtein
> Sent: Wednesday, May 09, 2012 15:00
> To: [e-mail]
> Cc: [e-mail]
> Subject: Re: [PWE3] once upon an erratum
> 
> Stewart,
> It is Section 9 of RFC 5063 (not 5061!)  that discusses service-delimiting
> modes and their mapping to the appropriate set of the PW attributes.
> 
> I apologize for the typo.
> 
> Regards,
>      Sasha
> ________________________________________
> From: [e-mail] [[e-mail]] on behalf of
> Stewart Bryant [[e-mail]]
> Sent: Wednesday, May 09, 2012 12:17 PM
> To: [e-mail]
> Subject: Re: [PWE3] once upon an erratum
> 
> Sasha
> 
> Do you have the correct reference? If so perhaps you could
> point to the right section.
> 
> Stewart
> 
> 
> Yaakov
> 
> I think that the purpose of the text as to say that the tag
> may or may not be service delimiting, which I think is
> demonstrably true.
> 
> Stewart
> 
> 
> 
> On 08/05/2012 12:20, Alexander Vainshtein wrote:
> >
> > Yaakov, Stewart and all,
> >
> > I believe that 5061 effectively supports Yaakov's point of view.
> >
> > My 2c,
> >
> > Sasha
> >
> > *From:*[e-mail] [mailto:[e-mail]] *On
> Behalf
> > Of *Yaakov Stein
> > *Sent:* Tuesday, May 08, 2012 1:59 PM
> > *To:* Stewart Bryant; [e-mail]
> > *Subject:* [PWE3] once upon an erratum
> >
> > Stewart and all,
> >
> > RFC 4448 has an erratum marked "Held for Document Update by Stewart
> > Bryant".
> >
> > This erratum (penned by Alfred Hoenes) deals with several issues,
> >
> > from a "subtle typo" to the misleading figure label.
> >
> > However, there is one issue with which I agree and which I think is
> > important;
> >
> > but regarding which I don't recall discussion on the list.
> >
> > With the entire group of comments marked as "held for document
> update"
> > rather than as "approved",
> >
> > I am not sure whether this issue has been agreed upon.
> >
> > The text in question is this :
> >
> > When the PE receives an Ethernet frame, and the frame has a VLAN tag,
> >
> > we can distinguish two cases:
> >
> > 1. The tag is service-delimiting. This means that the tag was
> >
> > placed on the frame by some piece of service provider-operated
> >
> > equipment, and the tag is used by the service provider to
> >
> > distinguish the traffic. For example, LANs from different
> >
> > customers might be attached to the same service provider
> >
> > switch, which applies VLAN tags to distinguish one customer's
> >
> > traffic from another's, and then forwards the frames to the PE.
> >
> > 2. The tag is not service-delimiting. This means that the tag was
> >
> > placed in the frame by a piece of customer equipment, and is
> >
> > not meaningful to the PE.
> >
> > Alfred states that
> >
> > The term, "service delimiting", apparently here is defined
> > by the origin of the tag, not by its function.
> >
> > I understand where the original text comes from.
> >
> > In the provider provisioned model the SP doesn't trust the customer to
> > properly tag the frames,
> >
> > and so doesn't look at tags inserted by CE devices.
> >
> > However, other groups (e.g., MEF) assume careful prior negotiation
> >
> > (of the legal kind, not the protocol kind) between customer and SP,
> >
> > and so the C-tag may indeed be service delimiting.
> >
> > More specifically, one can make the distinction between three
> > "bundling" types
> >
> > based on the C-tag.
> >
> > *All-to-one means that all C-tags are taken as one "flow" or "EVC" or
> > whatever,
> >
> > and thus the mapping to PW is independent of this tag.
> >
> > So here the C-tag is NOT service delimiting.
> >
> > *One-to-one means that each C-tag is mapped to a single EVC.
> >
> > So the C-tag determines the PW, and is thus service delimiting.
> >
> > *Arbitrary bundling means we have a general mapping
> >
> > of C-tags to EVCs (and so includes the previous two).
> >
> > In general the C-tag here too is service delimiting.
> >
> > (NOTE: the arbitrary and One-to-one cases are lumped together in MEF as
> >
> > the "bundling" case.)
> >
> > Do you agree with this analysis, and thus with the need to remove the
> > caveat in 4448
> >
> > that states that C-tags can not be service delimiting ?
> >
> > Y(J)S
> >
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