Re: [mpls-tp] [PWE3] [mpls] WG LC draft-lm-pwe3-mpls-tp-gal-in-pw-00.txt

[Thomas Nadeau <[e-mail]>]

> Hi,
> AFAIK, ACH can't be used without supporting the CW in HW.
> 
> As per RFC-5085, 5.1.1.  In-Band VCCV (Type 1)
> CC Type-1 mode of VCCV operation MUST be supported when the control word is present.
> 
> Are we implicitly mandating the CW (ACH) in HW by configuring/negotiating the CC type-4?
> It looks to me that CC type-1 for ACH without GAL and CC type-4 for ACH with GAL.

	The IETF's protocols do not mandate how they are to be implemented per se (i.e.:
in HW or not). The draft addresses the operational concerns of configuration/complexity 
by having 1 mode for each of the major operational scenarios: with or without the CW.

> IMO, if we support CC type-4, CC type-1 support is implicitly attained.
> 
> IMHO, it should be possible to get the MPLS-TP OAM control packets with or without GAL from HW to CP by negotiating CC type-1 itself.

	There is no negotiation; VCCV uses a capability advertisement. But more to the point, 
the proposed operation rule here is simple and straight-forward: if you have configured the CW and advertised 
that as per the rules for use of the CW, then Type 1 MUST be used. If not, use Type 4 (if both sides are capable).  

> Some editorial comments for the draft-nadeau-pwe3-vccv-2-01.txt draft,
> "
> 4.1.1.  MPLS VCCV Control Channel (CC) Type 4
> 
>    IANA is requested to augment the registry of "MPLS VCCV Control
>    Channel Types" with the new type defined below. As defined in
>    RFC5058, this new bitfield is to be assigned by IANA using
> "
> Replace the RFC5058 as RFC5085.

	Cool, thanks. We will fix this in the next rev.

	--Tom


> 
> Thanks,
> Venkat.
> 
> On Fri, Mar 11, 2011 at 2:21 PM, Alexander Vainshtein <[e-mail]> wrote:
> Greg, Luca,
> 
> As I’ve already stated in my comment on draft-nadeau-pwe3-vccv-2, IMHO it makes draft-lm-pwe3-mpls-tp-gal-in-pw completely useless.
> 
>  
> My 2c,
> 
>      Sasha
> 
>  
> From: [e-mail] [mailto:[e-mail]] On Behalf Of Greg Mirsky
> Sent: Friday, March 11, 2011 9:14 PM
> To: Luca Martini
> Cc: [e-mail]; [e-mail]; pwe3; HUANG Feng F; [e-mail]
> Subject: Re: [mpls] WG LC draft-lm-pwe3-mpls-tp-gal-in-pw-00.txt
> 
>  
> Dear Luca,
> thank you for bringing draft-nadeau-pwe3-vccv-2-01 to my attention. I'll send my comments to it in a separate e-mail.
> I'll have to miss another opportunity to discuss your proposal in a meeting. Please add my comments below to my earlier expressed WG LC comments:
> 
> the draft-lm-pwe3-mpls-tp-gal-in-pw-00 depends on any solution that addresses applicability of GAL in PW VCCV, e.g. solution proposed in draft-nadeau-pwe3-vccv-2-01;
> the draft-lm-pwe3-mpls-tp-gal-in-pw-00 needs to mention such dependency and refer to any existing proposal;
> I believe that the draft-lm-pwe3-mpls-tp-gal-in-pw-00 can be advanced in lock with document that addresses use of GAL in PW VCCV.
> Regards,
> Greg
> 
> On Fri, Mar 11, 2011 at 5:31 AM, Luca Martini <[e-mail]> wrote:
> 
> Greg ,
> Some
> 
> 
> On 02/18/11 11:15, Greg Mirsky wrote:
> > Dear Luca,
> > I see at least two issues:
> >
> >     * use of GAL for PW, in my view, is another VCCV CC type that has
> >       to be negotiated as described in RFC 5085.
> >
> 
> These are valid points, but this document in question does not define,
> not discussed VCCV.
> We have since posted a draft that proposes a new VCCV mode , and we
> welcome comments regarding that document.
> (draft-nadeau-pwe3-vccv-2-01.txt)
> 
> >     * use of GAL creates ambiguous situation when PW CW is used. The
> 
> >       benefit from extending GAL in PW, as I see, is for PWs that are
> >       not required to use PW CW. That might be a good enough reason to
> >       update RFC 5586 as proposed in the document but we must address
> >       use cases of GAL in PWs that require presence PW CW. If we
> >       prohibit or even discourage use of GAL for these PWs that have
> >       PW VCCV as native Associated Channel, then architecture of ACh
> >       for MPLS-TP PW not simplified as result of adopting the proposal.
> >
> > Regard
> 
> Greg,
> The GAL is basically a notifier that the packet following the end of the
> MPLS label stack, is explicitly defined as a G-ACH format.
> Normally the packet would be decoded as an IP packet , unless the last
> label on the stack indicated otherwise.
> 
> The GAL can certainly be applied  to a PW OAM packet on a PW that uses
> the CW, and this document does not define that , nor restricts it.
> 
> The scope of this document is limited to removing an unnecessary
> restriction in rfc5586, hence  this comment not applicable to this document.
> 
> Thanks.
> Luca
> 
> 
> > s,
> > Greg
> >
> > On Fri, Feb 18, 2011 at 7:46 AM, Luca Martini <[e-mail]
> 
> > <mailto:[e-mail]>> wrote:
> >
> >     Greg,
> >
> >     Sorry, but I do not remember the point you mention.
> >     Can you explain again here ?
> >     Thanks.
> >     Luca
> >
> >
> >     On 02/17/11 23:47, Greg Mirsky wrote:
> >     > Dear Authors and All,
> >     > prior to the meeting in Bejing and acceptance of this proposal as WG
> >     > document Luca and I agreed that use of GAL with PW VCCV presents a
> >     > problem.
> >     > I was not attending the IETF-79, nor I found discussion of this
> >     issue
> >     > in the minutes. I think that this issue should be specified,
> >     > explained. In my view, this document updates not only RFC 5586
> >     > but RFC 5085 too.
> >     >
> >     > Regards,
> >     > Greg
> >     >
> >     > Comment to draft-lm-pwe3-mpls-tp-gal-in-pw-00.txt
> >     >
> >     > On Sat, Oct 30, 2010 at 10:14 AM, Luca Martini
> >     <[e-mail] <mailto:[e-mail]>
> 
> >     > <mailto:[e-mail] <mailto:[e-mail]>>> wrote:
> >     >
> >     >     Greg,
> >     >
> >     >     You are correct , the proposed update does not propose any
> >     changes
> >     >     to VCCV.
> >     >     However the problem with vccv is not as simple as to ask for
> >     a new
> >     >     code point from IANA.
> >     >     Given the good amount of discussion on this point, we should
> >     >     probably have a discussion in Beijing.
> >     >
> >     >     Luca
> >     >
> >     >
> >     >
> >     >     On 10/29/2010 05:07 PM, Greg Mirsky wrote:
> >     >>     Dear Authors,
> >     >>     I think that proposed update of the Section 4.2. RFC 5586
> >     makes it possible
> >     >>     to use GAL on MPLS-TP PW that uses Control Word. I consider
> >     it to be
> >     >>     conflict between PW VCCV CC types because use of GAL is not
> >     negotiated
> >     >>     through PW VCCV negotiation. To avoid such situation I propose:
> >     >>
> >     >>        - in Section 5 request IANA to assign new CC Type "MPLS
> >     Generic
> >     >>        Associated Channel Label"
> >     >>        - assign precedence to new CC Type that affects Section
> >     7 RFC 5085
> >     >>
> >     >>     Regards,
> >     >>     Greg
> >     >>
> >     >>
> >     >>
> >     >>     _______________________________________________
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> 
> >     >>     [e-mail] <mailto:[e-mail]> <mailto:[e-mail]
> 
> >     <mailto:[e-mail]>>
> >     >>     https://www.ietf.org/mailman/listinfo/mpls
> >     >
> >     >
> >     >
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> >
> >
> 
> 
>  
> 
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> 
> 
> -- 
> Best Regards,
> Venkatesan Mahalingam.
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