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

[Maarten vissers <[e-mail]>]

Nurit,

If I translate your proposal in terms of SDH protection, then your proposal would imply that LOVC (e.g. VC-12, VC-11 protection should not be deployed, instead only HOVC (VC-4, VC-3) protection should be deployed. We all know that the SDH network has many protected LOVC connections, and that this is scaling well. My question is therefore why protecting MS-PW connections (and Service-LSP connections) would not scale?

Regards,
Maarten

From: [e-mail] [mailto:[e-mail]] On Behalf Of Sprecher, Nurit (NSN - IL/Hod HaSharon)
Sent: 13 June 2011 15:02
To: ext Alexander Vainshtein; [e-mail]
Cc: [e-mail]; [e-mail]
Subject: Re: [mpls] [PWE3] Seeking feedback on I-D "MPLS-TP LinearProtection Applicability to MS-PW"

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: [e-mail] [mailto:[e-mail]] On Behalf Of ext Alexander Vainshtein
Sent: Monday, June 13, 2011 3:43 PM
To: [e-mail]
Cc: [e-mail]; [e-mail]
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: [e-mail] [mailto:[e-mail]] On Behalf Of [e-mail]
Sent: Monday, June 13, 2011 3:25 PM
To: [e-mail]
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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