RE: [PWE3] BFD for MPLS PWs

["Busschbach, Peter B (Peter)" <busschbach at lucent.com>]

To move the discussion forward, let me follow up on my own question.

I believe that there is a broad concensus that insertion of AIS, as mandated by draft-ietf-pwe3-atm-encap-11, implies that the PE will NOT send an additional PW Status message to report the same defect.

RFC 4447 states "The PW status signaling procedures described in this section MUST be fully implemented." The document itself, however, specifies HOW to use PW Status signaling but is vague about WHEN to use PW Status signaling. The latter is addressed in the encapsulation drafts, such as atm-encap, and is fully defined in OAM-MAP (draft-ietf-pwe3-oam-msg-map-04).

The notion that RFC 4447 should be interpreted as a mandate to send a PW Status message for every single defect is an incorrect interpretation of the spirit of the standard, does not reflect WG concensus and, if implemented, would lead to inefficient implementations.

Therefore, I strongly disagree with the point of view that Tom and Luca have formulated regarding the use of BFD for both fault detection and status signaling. When this option is used, there is, IMO, no need to send PW Status messages. The current text of OAM-MAP is in line with this view.

Peter

> -----Original Message-----
> From: Busschbach, Peter B (Peter) [mailto:busschbach at lucent.com]
> Sent: Wednesday, August 16, 2006 4:40 PM
> To: 'Luca Martini'
> Cc: Swallow George; 'Thomas D. Nadeau'; Pignataro Carlos; Morrow
> Monique; pwe3 WG ((((((((E-mail)))))))); Danny McPherson; 
> Agarwal Rahul;
> Stewart (stbryant) Bryant
> Subject: RE: [PWE3] BFD for MPLS PWs
> 
> 
> Luca,
> 
> Section 7.4 of the ATM Encapsulation draft 
> (draft-ietf-pwe3-atm-encap-11.txt) mandates that upon LOS the 
> ingress PE inserts F4 AIS for every affected VPC. Is it your 
> opinion that because of RFC 4447 the ingress PE must send a 
> PW Status message in addition to F AIS insertion?
> 
> Peter
> 
> > -----Original Message-----
> > From: Luca Martini [mailto:lmartini at cisco.com]
> > Sent: Tuesday, August 15, 2006 6:29 PM
> > To: Busschbach, Peter B (Peter)
> > Cc: 'Thomas D. Nadeau'; Swallow George; Pignataro Carlos; Morrow
> > Monique; pwe3 WG ((((((((E-mail)))))))); Danny McPherson; 
> > Agarwal Rahul;
> > Stewart (stbryant) Bryant
> > Subject: Re: [PWE3] BFD for MPLS PWs
> > 
> > 
> > Busschbach, Peter B (Peter) wrote:
> > >
> > > In my opinion, the work on VCCV and OAM-MAP provides a 
> > further specification of RFC4447 and in fact overrules the 
> > requirement that LDP Status signaling must be used.
> > >
> > >
> > >   
> > Peter, 
> > We agreed a long time ago that the LDP status messaging was 
> > going to be mandatory , in fact people insisted I make it mandatory.
> > So I would have to say that the LDP status MUST always be 
> > used as mandated in RFC 4447, and the BFD status messaging is 
> > an optional, and , in my opinion, not a very useful option 
> > when LDP is in use.
> > 
> > Luca
> > 
> > 
> > > A minor comment on your email:
> > > I am not sure what you mean by the "de-facto status must 
> > always rely on LDP". Either you declare that that the PW is 
> > down when (1) BFD OR LSP indicate a PW failure, or (2) based 
> > only on the LDP status. In my mind "de-facto status" implies 
> > (2), whereas the beginning of your email says that (1) is the 
> > proposed procedure.
> > >
> > > Peter
> > >  
> > >
> > > _______________________________________________
> > > pwe3 mailing list
> > > pwe3 at ietf.org
> > > https://www1.ietf.org/mailman/listinfo/pwe3
> > >   
> > 
> 
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