PMP Mail Archive: PMP> Printer MIB questions from the field

PMP Mail Archive: PMP> Printer MIB questions from the field

PMP> Printer MIB questions from the field

Harry Lewis (harryl@vnet.ibm.com)
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
pmp@pwg.org. You can also subscribe by sending mail to
majordomo@pwg.org 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