Subject: PMP> Printer MIB questions from the field

From: "Harry Lewis <[email-masked]>" <[email-masked]>
Date: Thu, 20 Feb 97 08:23:57 MST

On Saturday, 2/15, Harish Nachnani wrote (to the WINSNMP reflector):

>The Printer mib rfc (15xx ) refers to the host resource mib objects.
>Does that mean that if one was implementing the printer mib support,
>he/she would also have to provide support for host resource mib.
>Should all the objects of the host resource mib be supported for a
>printer or only the objects related to printer device be supported ?

Harish, first, please let me suggest that one of the Printer Working
Group (PWG) e-mail reflectors would be a better place to seek this
type of advice. Most likely, you should direct questions regarding the
printer MIB (RFC1759), it's components and/or evolution to
[email-masked]. You can also subscribe by sending mail to
[email-masked] with "Subscribe PMP" in the body of your mail msg.

Now, to try an answer your question about the Printer MIB (RFC1759)
and the Host Resources MIB (RFC1514).

Yes, a Printer MIB agent must implement portions of the HR MIB (as
well as portions of MIB-II - the System and Interfaces groups).

Specifically, the Printer MIB calls out support for the hrSystem Group
(although recent interoperability testing has shown this to be of
little use to printers), hrStorage Group and hrDevice Group.

hrDeviceID is *integral* to any implementation of the Printer MIB.
hrDeviceID uniquely identifies a specific printer model within a
vendors product family. By identifying the hrDeviceID, a Management
Application can determine which printer model is at the other end
of the line (i.e. for self-configuring print drivers as an example).

Also, hrDeviceIndex is fundamental to the Printer MIB implementation.
The HR MIB hrDeviceTable contains an entry for every device, including
device type PRINTER. Developers of RFC1759 did not limit their scope
to simple one-to-one relationships of SNMP agent to printer. They also
considered "fan-in" - one printer (agent) serving multiple interfaces,
and "fan-out" - one network interface serving (directly attached)
printers. In the later case, the SNMP agent is in the "external network
adapter" and serves as the Printer MIB agent for both printers.

Thus, every response from the Printer MIB agent is indexed by
hrDeviceIndex, thereby pointing to which "printer device" the response
corresponds to. It would have been much simpler *NOT* to consider
fan-in or fan-out, however, these were prevalent situations in the
industry at the time RFC1759 was under development (and still exist).

It's somewhat difficult to see the relationship of MIB-II interfaces
table to "fan-in" and hrDeviceIndex to "fan-out". Recent
interoperability testing has demonstrated this, and the PWG Printer
MIB Project is discussing this topic now. You may want to subscribe
to learn where things are headed in terms of clarification.

I hope this helps answer your question

Harry Lewis - IBM Printing Systems

---

From: [email-masked] (Bill Wagner)
Date: Thu, 20 Feb 1997 18:57:11 -0500

Matt, 
     
     This specific question came up very pointedly when the HRMIB groups 
     were suggested for inclusion by reference. Hopefully Steve Waldbusser 
     will substantiate my recollection that the reference was considered as 
     being to a group definition in a different MIB, and was at the group 
     level, not the MIB level. This was perhaps akin to using textual 
     conventions defined in some other MIB. Therefore, requirements of the 
     MIB from which the group was copped are not inherently transferred.
     
     With this interpretation, such inclusion is as part of the printer MIB 
     and does not constitute compliant implementation of the HR MIB. 
     Whether a manufacturer wants to implement the HR MIB and what 
     constitutes compliant implementation of the HR MIB seems a completely 
     different question and has no bearing on compliant implementation of 
     the Printer MIB.

     Bill Wagner, DPI

______________________________ Reply Separator _________________________________
Subject: Re: PMP> Printer MIB questions from the field
Author:  [email-masked] at Internet
Date:    2/20/97 12:58 PM

Bill,

WARNING: Philosophical statement ahead!

If rfc1514 states that the System group (along with the Storage and
Device groups) are mandatory, can rfc1759 make the System group optional
when used in conjunction with Printer-MIB?  If so, when a vendor
implements only the Storage and Device groups, did they implement the
Host Resources MIB?

--Matt King

Bill Wagner wrote:
> 
> 
>         Harry,
> 
>         Just one note on your excellent summary. Relative to your statement:
> 
>       As far as I can ascertain, RFC1759 does not call out support for the
> hrSystem group (other than saying that this group, along with Running
Software,
> etc. can be implemented at the discression of the manufacturer). Perhaps the
> conclusion of the interopability testing  just confirms what was considerd in
> the printer MIB originally.
> 
> Bill Wagner, DPI

-- 
Matt King                                     Opinions are my own and
Staff Engineer                                    are not necessarily
Lexmark International, Inc.                          those of Lexmark
[email-masked]