PMP Mail Archive: PMP> RE: question about the printer mib

PMP Mail Archive: PMP> RE: question about the printer mib

PMP> RE: question about the printer mib

From: McDonald, Ira (imcdonald@sharplabs.com)
Date: Thu Feb 21 2002 - 16:55:34 EST

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    Hi Juergen,

    But you are asking for a backwards incompatible change in the module
    compliance definitions (which is illegal under SMI rules).

    RFC 1759 lists 'prtMarkerGroup' in the MANDATORY-GROUPS clause of
    the 'prtMIBCompliance' MODULE-COMPLIANCE macro.
    And 'prtMarkerGroup' lists 'prtMarkerLifeCount' as a mandatory
    object to implement.

    So a printer _cannot_ conform to Printer MIB v1 and not implement
    'prtMarkerLifeCount'.

    I sympathize with your problem, but you didn't point this problem
    out 8 years ago (when Steve Waldbusser wrote the ASN.1 that way).

    So for backwards compatiblity, the best we can do is to STRONGLY
    RECOMMEND (in the object definition) that the object be persistent
    in all printers (across power cycles) and to add your (excellent)
    clarification that the two counters are zero-based and _when_
    they are initialized to zero.

    OK?

    Cheers,
    - Ira McDonald, co-editor of Printer MIB v2
      High North Inc
      imcdonald@sharplabs.com

    -----Original Message-----
    From: Juergen Schoenwaelder [mailto:schoenw@ibr.cs.tu-bs.de]
    Sent: Thursday, February 21, 2002 5:02 AM
    To: imcdonald@sharplabs.com
    Cc: imcdonald@sharplabs.com; pmp@pwg.org; Ron.Bergman@Hitachi-hkis.com;
    bwijnen@lucent.com
    Subject: Re: question about the printer mib

    >>>>> McDonald, Ira writes:

    Ira> I agree with you that 'prtMarkerLifeCount' SHOULD be persistent.
    Ira> And that's what RFC 1759 (Printer MIB v1) said in the same words
    Ira> used in the latest Printer MIB v2 draft, but in section 2.3, not
    Ira> in the object definition itself.

    I think it MUST be persistent to be useful.

    Ira> Back in 1994, the chance that a low-end printer might have
    Ira> trouble supporting persistent counters was probably much higher.

    So these printers do not implement this object. I prefer to get no
    number rather than a wrong number.

    Ira> I would suggest that you may actually safely assume that the
    Ira> 'prtMarkerLifeCount' _is_ persistent, because I've never heard of
    Ira> a modern printer where it is not persistent.

    Ira> Should we improve the DESCRIPTION clause of 'prtMarkerLifeCount'
    Ira> to explicitly add something like:

    Ira> "Note: This object SHOULD be implemented as a persistent
    Ira> object with a reliable value throughout the lifetime of the
    Ira> printer."

    This thread started because I was not sure (from looking at the object
    definition) if these counters are indeed zero-based. Here is a what
    would have helped me:

    prtMarkerLifeCount OBJECT-TYPE
        SYNTAX Counter32
        MAX-ACCESS read-only
        STATUS current
        DESCRIPTION
            "The count of the number of units of measure counted during
            the life of printer using units of measure as specified by
            prtMarkerCounterUnit. This counters starts at zero when the
            printer is manufactured and is persistent throughout the
            lifetime of the printer."
        ::= { prtMarkerEntry 4 }

    prtMarkerPowerOnCount OBJECT-TYPE
        SYNTAX Counter32
        MAX-ACCESS read-only
        STATUS current
        DESCRIPTION
            "The count of the number of units of measure counted since the
            equipment was most recently powered on using units of measure as
            specified by prtMarkerCounterUnit. This counters starts at zero
            when the printer is powered on."
        ::= { prtMarkerEntry 5 }

    This still leaves it to some extend open under which conditions
    prtMarkerPowerOnCount is reset to zero when you play around with the
    various prtGeneralReset values (but this is not really a problem I
    care about at the moment).

    If people really care about printers without persistent memory,
    then the right thing to do would IMHO be to say in the compliance
    definitions that prtMarkerLifeCount is only required on printers
    that have persistent memory.

    /js

    -- 
    Juergen Schoenwaelder      University of Osnabrueck
    <schoenw@inf.uos.de>       Dept. of Mathematics and Computer Science
    Phone: +49 541 969 2483    Albrechtstr. 28, 49069 Osnabrueck, Germany
    Fax:   +49 541 969 2770    <http://www.informatik.uni-osnabrueck.de/>
    



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