Re: [mpls] [PWE3] Seeking feedback on I-D "MPLS-TP LinearProtection Applicability to MS-PW"

Hello,

Though on one side I'd think its costlier to do a MS-PW level protection
considering the resource usages, pre-configuration and monitoring overload,
on the other i would think - why wouldn't having such a mechanism help in
case if a local repair procedure fails ( failure in protection switch) for a
underlying broken LSP or a mid-PW segment. A provider would never hesitate
look into his pocket to have an end-end level protection considering a risky
situation for an high priority service that he runs on the MS-PW. Wouldn't
he? I believe he could be only concerned in the view of giving precedence to
efficient switching the server layers, and not messing up with multiple
switches happening for one failure.

-Binny.

On 13 June 2011 18:32, Sprecher, Nurit (NSN - IL/Hod HaSharon) <
nurit.sprecher@nsn.com> wrote:

> Hi,
>
> I would like to second Sasha.
>
> End-to-end PW protection (with diverse paths) does not scale, and put hard
> restrictions on the utilization of the resources.
>
> MPLS-TP PWs are carried across the network inside MPLS-TP LSPs. Therefore,
> an obvious way to provide protection for a PW is to protect the LSP that
> carries it.
>
> If the PW is a multi-segment PW, then LSP recovery can only protect the PW
> in individual segments.  This means that a single LSP recovery action cannot
> protect against a failure of a PW switching point (an S-PE).
>
> When protecting against an AC or T/S-PE failure by dual connectivity, PW
> redundancy mechanisms provide means for the PEs to coordinate over which LSP
> the traffic of the PW is carried.
>
> I also doubt why there is a need for additional mechanism.
>
> Best regards,
>
> Nurit
>
>
>
> *From:* pwe3-bounces@ietf.org [mailto:pwe3-bounces@ietf.org] *On Behalf Of
> *ext Alexander Vainshtein
> *Sent:* Monday, June 13, 2011 3:43 PM
> *To:* ma.yuxia@zte.com.cn
> *Cc:* mpls@ietf.org; pwe3@ietf.org
> *Subject:* Re: [PWE3] [mpls] Seeking feedback on I-D "MPLS-TP
> LinearProtection Applicability to MS-PW"
>
>
>
> Dear Ma and all,
>
> Adding the PWE3 WG to my response.
>
>
>
> The PW redundancy mechanism supports linear protection of MS-PWs as one of
> many additional application use cases:
>
> Appendix A of the PW redundancy Bit draft<http://datatracker.ietf.org/doc/draft-ietf-pwe3-redundancy-bit/?include_text=1>describes 5 application uses cases in addition to MS-PW with single-homed
> CEs (which is listed there as use case 5).
>
> And it is equally applicable to IP/MPLS and MPLS - with the help of  the Static
> PW Status Messages draft<http://datatracker.ietf.org/doc/draft-ietf-pwe3-static-pw-status/?include_text=1>(
> if, for whatever reason, you do not want  to, or cannot, use RFC 4447<http://datatracker.ietf.org/doc/rfc4447/?include_text=1>
> ).
>
>
>
> Hence I doubt the need for yet another PW redundancy  mechanism with narrow
> scope of applicability.
>
>
>
> Regards,
>
>      Sasha
>
>
>
> *From:* mpls-bounces@ietf.org [mailto:mpls-bounces@ietf.org] *On Behalf Of
> *ma.yuxia@zte.com.cn
> *Sent:* Monday, June 13, 2011 3:25 PM
> *To:* mpls@ietf.org
> *Subject:* Re: [mpls] Seeking feedback on I-D "MPLS-TP Linear Protection
> Applicability to MS-PW"
>
>
>
> Hi all,
>
> The linear protection mechanism for LSP and PW(including MS-PW) should be
> the same and it is valuable to describe it clearly.
>
> BTW, there is a typo, it is "T-PE Z" instead of "T-PE B".
>
>  "
>   Figure 1 illustrates such a scenario, where two MS-PWs are
>   established between T-PE A and T-PE B, over S-PEs 1-2 and 3-4
>   respectively. Each PW segment is established over an LSP (e.g. PW-
>   s12 over LSP12).
>  "
>
> -----Original Message-----
> From: Daniel Cohn
> Sent: Tuesday, May 17, 2011 4:14 PM
> To: mpls
> Subject: Seeking feedback on I-D "MPLS-TP Linear Protection
> Applicability to MS-PW"
> Importance: High
>
> Hi MPLSers,
>
> I uploaded "MPLS-TP Linear Protection Applicability to MS-PW" I-D
> (http://tools.ietf.org/html/draft-cohn-mpls-tp-pw-protection-00)
>
> The abstract goes:
>
> One of the requirements of the MPLS transport profile [RFC 5654] is
> to provide linear protection for transport paths, which include both
> LSPs and PWs. The functional architecture described in [SurvivFwk]
> is applicable to both LSP and PWs, however [LinearProt] does not
> explicitly describe mechanisms for PW protection in MPLS-TP.
>
> This document extends the applicability of the linear protection
> mechanism described in [LinearProt] to MPLS-TP segmented PWs
> (MS-PWs) as defined in [RFC 6073].
>
> Could you please review it and send feedback to the mailing list or
> directly to the author?
>
> Looking forward to your feedback,
>
> Daniel
>
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