rfc1759.txt

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   contain many different identifiable sub-mechanisms such as media
   movement devices, media buffers, duplexing units and interlocks. Not
   all of the various sub-mechanisms reside on every media path.  For
   example, one media path may provide printing only on one surface of
   the media (a simplex path) and another media path may have a sub-
   mechanism that turns the media over and feeds it a second time
   through the marker sub-unit (a duplex path).  The duplex path may
   even have a buffer sub-mechanism that allows multiple copies of the
   obverse side to be held before the reverse side of all the copies are
   marked.

2.2.8.  System Controller

   The System Controller is the sub-unit upon which the software
   components of the Printer run. The System Controller is represented
   in the model by the Host MIB. This MIB allows for the specification
   of the processor(s), memory, disk storage, file system and other
   underlying sub-mechanisms of the printer. The controller can range
   from simple single processor systems to multiprocessor systems. In
   addition, controllers can have a full range of resources such as hard
   disks. The printer is modeled to have one system controller even
   though it may have more than one processor and multiple other
   resources associated with it.

2.2.9.  Interfaces

   An interface is the communications port and associated protocols that
   are responsible for the transport of data to the printer. A printer
   has one or more interface sub-units. The interfaces are represented
   by the Interfaces Group of MIB-II (RFC 1213). Some examples of



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   interfaces are serial ports (with little or no protocol) and EtherNet
   ports on which one might run InterNet IP, Novell IPX, etc.

2.2.10.  Channels

   The channel sub-units identify the independent sources of print data
   (here print data is the information that is used to construct printed
   pages and may have both data and control aspects).  A printer may
   have one or more channels. The channel sub-units are represented by
   the Channel Group in the Model. Each channel is typically identified
   by the electronic path and service protocol used to deliver print
   data to the printer. A channel sub-unit may be independently enabled
   (allowing print data to flow) or disabled (stopping the flow of print
   data). It has a current Control Language which can be used to specify
   which interpreter is to be used for the print data and to query and
   change environment variables used by the interpreters (and SNMP).
   There is also a default interpreter that is to be used if an
   interpreter is not explicitly specified using the Control Language.
   Channel sub-units are based on an underlying interface.

2.2.11.  Interpreters

   The interpreter sub-units are responsible for the conversion of a
   description of intended print instances into images that are to be
   marked on the media. A printer may have one or more interpreters. The
   interpreter sub-units are represented by the Interpreter Group in the
   Model. Each interpreter is generally implemented with software
   running on the System Controller sub-unit. The Interpreter Table has
   one entry per interpreter where the interpreters include both Page
   Description Language (PDL) Interpreters and Control Language
   Interpreters.

2.2.12.  Console

   Many printers have a console on the printer, the operator console,
   that is used to display and modify the state of the printer.  The
   console can be as simple as a few indicators and switches or as
   complicated as full screen displays and keyboards. There can be at
   most one such console.  This console sub-unit is represented by the
   Console Group in the model.  Although most of the information
   displayed there is also available in the state of the printer as
   represented by the various Groups, it is useful to be able to query
   and modify the operator console remotely.  For example, a management
   application might like to display to its user the current message on
   the operator console of the remote printer or the management
   application user might like to modify the current message on the
   operators console of the remote printer.  As another example, one
   might have a remote application that puts up a pseudo console on a



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   workstation screen. Since the rules by which the printer state is
   mapped onto the console and vice versa are not standardized, it is
   not possible to reproduce the console state or the action of console
   buttons and menus. Therefore, the Console Group provides access to
   the console. The operator console is usually implemented on the
   system controller with additional hardware for input and display.

2.2.13.  Alerts

   The alert sub-unit is responsible for detecting reportable events,
   making an entry in the alert table and, if and only if the event is a
   critical event, initiating a trap. The alert sub-unit is represented
   by the Alerts Group and, in particular, the Alert Table. This table
   contains information on the severity, sub-unit, detailed location
   within the sub-unit, alert code and description of each critical
   alert that is currently active within the printer. Each reportable
   event causes an entry to be made in the Alert Table.

2.2.13.1.  Status and Alerts

   Summary information about the state of the printer is reported at
   three separate levels: (1) there is the status of the printer as a
   whole reported in the Host MIB, (2) there is the status of various
   sub-units reported in the principle table of the Group that
   represents the sub-unit, and (3) there are alert codes reported in
   the Alert Table.

2.2.13.2.  Overall Printer Status

   Of the many states a printer can be in, certain states are more
   "interesting" because of the distinct actions they are likely to
   provoke in the administrator.  These states may be applied to the
   printer as a whole, or to a particular sub-unit of the printer.
   These named states are:

   Non Critical Alert Active - For the printer this means that one or
   more sub-units have a non-critical alert active.  For a sub-unit,
   this means that the sub-unit has a non-critical alert active.

   Critical Alert Active - For the printer this means that one or more
   sub-units have a critical alert active.  For a sub-unit, this means
   that the sub-unit has a critical alert active.

   Unavailable - The printer or sub-unit is unavailable for use (this is
   the same as "broken" or "down" in other terminologies).  A trained
   service person is typically necessary to make it available.





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   Busy / Temporarily Unavailable - The printer or sub-unit is
   operational but currently occupied with a request for activity. The
   sub-unit will become available without the need of human interaction.

   Moving on-line or off-line - The printer is either off-line, in the
   process of moving off-line or in the process of moving back on-line;
   for example on high end printers reloading paper involves a
   transition to off-line to open the paper bin, it is then filled and,
   finally, there is a transition back to on-line as the paper bin is
   repositioned for printing.

   Standby - The printer or sub-unit is unavailable for use because it
   is partially powered down and may need some period of time to become
   fully operational again.  A unit in Standby state shall respond to
   network management requests.

   The Host MIB provides three status objects that can be used to
   describe the status of a printer: (1) hrDeviceStatus in the entry in
   the Host MIB hrDeviceTable; (2) hrPrinterStatus in the
   hrPrinterTable; and (3) hrPrinterDetectedErrorState in the
   hrPrinterTable.  These objects describe many of the states that a
   printer can be in.  The following table shows how the "interesting"
   states named above can be recognized by inspecting the values of the
   three printer-related objects in the Host MIB:

Printer     hrDeviceStatus  hrPrinterStatus  hrPrinterDetectedErrorState
Status

Normal         running(2)     idle(3)        none set

Busy/          running(2)     printing(4)
Temporarily
Unavailable

Non Critical   warning(3)     idle(3) or     could be: lowPaper,
Alert Active                  printing(4)    lowToner, or
                                             serviceRequested

Critical       down(5)        other(1)       could be: jammed,
Alert Active                                 noPaper, noToner,
                                             coverOpen, or
                                             serviceRequested

Unavailable    down(5)        other(1)

Moving off-    warning(3)     idle(3) or     offline
line                          printing(4)




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Off-line       down(5)        other(1)       offline

Moving         down(5)        warmup(5)
on-line

Standby        running(2)     other(1)

   These named states are only a subset of the possible states - they
   are not an exhaustive list of the possible states.  Nevertheless,
   several things should be noted.  When using these states, it is not
   possible to detect when both critical and non-critical alerts are
   pending - if both are pending, the Critical Alert Active state will
   prevail.  In addition, a printer in the Standby state will be
   represented in the Host MIB with a device status of running(2) and a
   printer status of other(1), a set of states that don't uniquely
   distinguish this important printer state.

   Although the above mapping is workable, it would be improved with a
   few additions to hrDeviceStatus and hrPrinterStatus in the Host
   Resources MIB. In particular, it would be appropriate to add a
   "standby" enumeration to hrDeviceStatus.  Similarly, it would be
   useful to add the following states to hrPrinterStatus: "offline" to
   indicate that reason for the printer being down (instead of having to
   use "other") which allows both "warning" and "offline" to indicate
   going offline and "down" and "offline" to indicate offline and
   "notApplicable" to cover cases, such as "standby", where the device
   state completely describes the state of the device.

   Detailed status per sub-unit is reported in the sub-unit status
   fields.

2.2.13.2.1.  Host MIB Printer Status

   For completeness, the definitions of the Printer Status objects of
   the Host MIB are given below:

      hrDeviceStatus OBJECT-TYPE
           SYNTAX  INTEGER {
                unknown(1),
                running(2),
                warning(3),
                testing(4),
                down(5)
           }
           ACCESS  read-only
           STATUS  mandatory
           DESCRIPTION
                 "The current operational state of the device



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                 described by this row of the table.  A value
                 unknown(1) indicates that the current state of the
                 device is unknown.  running(2) indicates that the
                 device is up and running and that no unusual error
                 conditions are known.  The warning(3) state
                 indicates that agent has been informed of an
                 unusual error condition by the operational software
                 (e.g., a disk device driver) but that the device is
                 still 'operational'.  An example would be high
                 number of soft errors on a disk.  A value of
                 testing(4), indicates that the device is not
                 available for use because it is in the testing
                 state.  The state of down(5) is used only when the
                 agent has been informed that the device is not
                 available for any use."
           ::= { hrDeviceEntry 5 }

   hrPrinterStatus OBJECT-TYPE
          SYNTAX INTEGER {
              other(1),
              unknown(2),
              idle(3),
              printing(4),
              warmup(5)
          }
          ACCESS read-only
          STATUS mandatory
          DESCRIPTION
                  "The current status of this printer device.  When
                  in the idle(1), printing(2), or warmup(3) state,