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

["Sprecher, Nurit (NSN - IL/Hod HaSharon)" <[e-mail]>]

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/?inclu
de_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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