Re: RFC3728 (1788) (RFC Errata System)

Hi Dan,

The proposed change is not a "change in semantics"
it is a correction for an incorrect UNIT clause.

In your message you state :
"If both dB and dBm are valid units"

They are not both valid in the context of a noise margin.
dB is a dimensionless quantity and dBm represents power
so they are not interchangeable.

Regards,

Scott

On Mon, 2009-06-01 at 10:36 +0200, Romascanu, Dan (Dan) wrote:
> I am afraid that such a change is not possible in an errata without
> deprecating the object and defining a new object. 
> 
> According to RFC 2578, Section 10.2 
> 
> (6)  A UNITS clause may be added.
> 
> It is not clear if the UNITS clause can just be changed as Menachem
> proposes. If both dB and dBm are valid units it looks like a change in
> the semantics of the object. Even if this was just a typo I doubt the
> change would be acceptable.
> 
> Deprecating an object and defining a new one requires a revision of the
> MIB module. Such change cannot be made in an errata. 
> 
> I would like to hear Bert's opinion. 
> 
> Dan
> 
> 
> 
> 
> > -----Original Message-----
> > From: [email protected] 
> > [mailto:[email protected]] On Behalf Of Menachem Dodge
> > Sent: Monday, June 01, 2009 9:59 AM
> > To: Scott Baillie; Bert Wijnen (IETF)
> > Cc: [email protected]
> > Subject: Re: [Adslmib] RFC3728 (1788) (RFC Errata System)
> > 
> > Hi,
> > 
> > So I believe there is now consensus that:
> >  
> >   The UNITS clause should be changed to "0.25dB" (instead of 
> > "0.25dBm").
> > 
> > No other changes are needed to any of the other clauses.
> > 
> > 
> > 
> > Are there any objections to accepting this errata? 
> > 
> > Best Regards,
> > Menachem
> > 
> > 
> > 
> > -----Original Message-----
> > From: [email protected] 
> > [mailto:[email protected]] On Behalf Of Scott Baillie
> > Sent: Thursday, May 28, 2009 8:07 PM
> > To: Bert Wijnen (IETF)
> > Cc: [email protected]
> > Subject: Re: [Adslmib] RFC3728 (1788) (RFC Errata System)
> > 
> > Hi All,
> > 
> > I think the UNITS clause should be changed to "0.25dB"
> > and this is not an incompatible change.
> > 
> > The MIB object in question holds a noise margin value and is 
> > expressed in dB. The MIB object does not represent a power 
> > level, it represents a ratio of power levels.
> > Because the MIB object represents a ratio there is no need to 
> > mention power levels at all in the UNITS clause or in the 
> > DESCRIPTION clause.
> > 
> > I have a few comments about some of the previous posts :
> > 
> > >Without an explicit or implicit reference level, decibel (dB) is 
> > >undefined as it represents a ratio.  In our case (as with the ITU 
> > >document), the reference level is explicitly specified in the UNITS 
> > >clause.  If it were not, it would be implied by the context. 
> >  That is, 
> > >we are measuring changes in audio levels in telephone 
> > circuits.  This 
> > >has a VERY long and established history (the bel is named after 
> > >Alexander Graham Bell, a decibel being one tenth of a bel).
> > 
> > I understand that it is convenient to use dBm when expressing 
> > power levels in telephone circuits but the MIB object in 
> > question is a noise margin, not a power level.
> > 
> > >However, if one felt forced, compelled, to be more specific, then, 
> > >changing "dB" in the DESCRIPTION clause to "dBm" would be the more 
> > >accurate change.
> > 
> > That change would be completely incorrect.
> > 
> > >Burt the reported proposal for the fix was going to change 
> > Integer32 to 
> > >Gaug32, or so I understood. That would be really bad I think.
> > 
> > No need to change the SYNTAX clause.
> > 
> > Regards,
> > 
> > Scott.
> > 
> > On Thu, 2009-05-28 at 00:01 +0200, Bert Wijnen (IETF) wrote:
> > > I can possibly live with updatinmg the description clause.
> > > Burt the reported proposal for the fix was going to change 
> > Integer32 
> > > to Gaug32, or so I understood. That would be really bad I think.
> > >  
> > > If the SYNTAXes and the value-ranges) all stay the same, 
> > then I guess 
> > > that formally it would still be a semantic change, but it 
> > is a matter 
> > > of wording change that I could probably accept if the WG really has 
> > > consensus on this.
> > >  
> > > Bert
> > >         ----- Original Message ----- 
> > >         From: Randy Presuhn 
> > >         To: [email protected] 
> > >         Sent: Wednesday, May 27, 2009 8:36 PM
> > >         Subject: Re: [Adslmib] RFC3728 (1788) (RFC Errata System)
> > >         
> > >         
> > >         Hi -
> > >         
> > >         > From: "Ray, Robert E. (MSFC-NNM05AB50C)"
> > >         <[email protected]>
> > >         > To: "Menachem Dodge" <[email protected]>;
> > >         "Romascanu, Dan (Dan)" <[email protected]>;
> > >         <[email protected]>
> > >         > Cc: <[email protected]>
> > >         > Sent: Wednesday, May 27, 2009 10:50 AM
> > >         > Subject: Re: [Adslmib] RFC3728 (1788) (RFC Errata System)
> > >         ...
> > >         > Because of this, I disagree completely with the 
> > Bert and Dan
> > >         on this because
> > >         > I don't think the semantics are changed at all.  
> > I think the
> > >         context, and hence
> > >         > the reference level, is completely stated.  We are, after
> > >         all, dealing with
> > >         > telephone wires.
> > >         
> > >         Agreed.
> > >         
> > >         > However, if one felt forced, compelled, to be 
> > more specific,
> > >         then, changing
> > >         > "dB" in the DESCRIPTION clause to "dBm" would be the more
> > >         accurate change.
> > >         ...
> > >         
> > >         Agreed.  It's a case of the notation used in the DESCRIPTION
> > >         clause
> > >         being well-understood within the specialist community, but
> > >         being
> > >         potentially ambiguous outside of that community.  If the
> > >         change
> > >         is deemed necessary, it's nothing more than a clarification.
> > >         
> > >         Randy
> > >         
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