Tom,

With regards to:

> 	It does make the state machine more complex, but not
> to the point where it cannot work. This is why we have the
> AND/OR processing text that we agreed to.  I am fixing this
> now.

In my opinion, the VCCV draft should not make any statements about the processing of fault notifications. This is addressed in detail in OAM-MAP. Trying to summarize it with a few sentences about AND/OR processing does not add anything and in the worse case might cause confusion and lead to incorrect interpretations.

In fact, the current version of OAM-MAP is quite clear about the procedures. Paragraph 6.1 says that a PE enters the PW forward defect state "if one of the following occurs" and that it exits that state when the previous defect indications have been cleared.

In essence this is the AND/OR procedure that you propose. However, it is more precise since it recognizes that a PE may transition from the forward defect state to the reverse defect state. I don't think you want to get into that level of detail in the VCCV draft and therefore it is better to just refer to OAM-MAP.

Peter

> -----Original Message-----
> From: Thomas D. Nadeau [mailto:tnadeau@cisco.com]
> Sent: Wednesday, August 16, 2006 7:58 AM
> To: Busschbach, Peter B (Peter)
> Cc: pwe3 WG ((((((((E-mail)))))))); Swallow George; Pignataro Carlos;
> Morrow Monique; Danny McPherson; Agarwal Rahul; Stewart (stbryant)
> Bryant
> Subject: Re: [PWE3] BFD for MPLS PWs
> 
> 
> 
> On Aug 15, 2006, at 3:35 PM, Busschbach, Peter B (Peter) wrote:
> 
> >
> > Tom,
> >
> > I have a comment on the following part of your proposed text:
> >
> >>     The defined values for CV Types are:
> >>
> >>         0x00  None.
> >>         0x01  ICMP Ping.
> >>         0x02  LSP Ping.
> >>         0x04  BFD for PW Fault Detection only.
> >>         0x08  BFD for PW Fault Detection and AC/PW Fault
> >>               Status Signaling.
> >>     It should be noted that two different CV Types have 
> been defined
> >>     when BFD is used. In the case of type 0x08, the AC and 
> PW status
> >>     SHOULD be conveyed via BFD status codes as specified in [OAM- 
> >> MAP].
> >>     However, this type SHOULD NOT be used when a control 
> protocl such
> >>     as LDP is available that can signal the AC/PW status to the  
> >> remote
> >>     endpoint of the PW due to complications that can arise from
> >>     synchronization issues between the control protocol's status
> >>     signaling messags and the BFD messages containing fault status
> >>     information.
> >>
> >
> > I don't think it is correct to mandate that 0x08 should not 
> be used  
> > if LDP is used to setup PWs. An operator might prefer to use BFD  
> > for both PW and AC fault notification, even if LDP is being used,  
> > because BFD is transported in the data plane whereas LDP is in the  
> > control plane. Since the control  plane is critical for correct  
> > operation of the network, it makes sense to avoid overloading it  
> > with data-plane-related  failure notifications.
> 
> 	That is true, and is why the text above says "SHOULD NOT"
> instead of "MUST NOT".  If the WG wants me to use lighter language
> I will.
> 
> > Furthermore, I don't understand which "complications" you 
> refer to.  
> > Using BFD for both AC and PW fault status information is more  
> > straightforward than using BFD for some faults and LDP for others.  
> > The only complication that I see is that a developer must read  
> > section 5.3.4 of OAM-MAP. If that text is ambiguous, it should be  
> > updated, but otherwise I don't see what is complicated about it.
> 
> 	It does make the state machine more complex, but not
> to the point where it cannot work. This is why we have the
> AND/OR processing text that we agreed to.  I am fixing this
> now.
> 
> 	--Tom
> 
> 
> >
> > Peter
> >
> > _______________________________________________
> > pwe3 mailing list
> > pwe3@ietf.org
> > https://www1.ietf.org/mailman/listinfo/pwe3
> 

_______________________________________________
pwe3 mailing list
pwe3@ietf.org
https://www1.ietf.org/mailman/listinfo/pwe3