1. Projector & Display Management WG Projector & Display Management WG Technical Notes - RBL Rick Landau, Dell, and the Projector & Display Management WG 2007/03/18

2. Projector & Display Management WG 2 General Discussions - Organizing Data for SNMP General discussion of the structure of management data (All) – How we organize the management data into functional groups, tables or repeating groups, and properties Discuss the need for meaningful Descriptions of properties (All) – A description that repeats the name does not add useful content. Discussion on naming conventions (Rick) – Generating SNMP from the XML poses some challenges. – Should Group be named XxxxGroup? – Should Table be named XxxxTable? – Should properties in tables be named XxxxDescription, XxxxStatus, etc.? – Use of upper and lower case.

3. Projector & Display Management WG 3 SNMP Table Structure Repeating objects are represented in rectangular tables – Rows are instances of the object – Columns are properties of the object – The intersection is the value of this property for this instance There are very few scalar (non-repeating) objects (For proxy management agents and providers, Projectors repeat!) (Index)DescriptionStatusSpeedReplacementPartNumber.1Intake fanOK123DP/N 12345A.2Outflow fanOK456DP/N 67890B

4. Projector & Display Management WG 4 Proposal: Simplify the Naming Should not use "Group" in a property name Should not use "Table" or "Entry" in a property name unless it is part of a table Group: Fan --> OID PWG-PROJECTOR-MIB.pdmFan – One Table: Fan --> pdmFan.pdmFanTable, pdmFan.pdmFanEntry, pdmFan.PdmFanEntry Property: Description --> pdmFanTable.pdmFanEntry.pdmFanDescription Property: Status --> pdmFanTable.pdmFanEntry.pdmFanStatus Etc.

5. Projector & Display Management WG 5 Proposal: Better Property Descriptions If the description simply repeats the name of the property, that does not give the programmer more information – Property: ZoomLevel – Description: "The zoom level of the projector." Tell the programmer what it actually does and how to use it -- PLEASE – Description: "The setting of the zoom adjustment of the projector, in arbitrary units. This property is implemented only if the zoom level can be electronically controlled by the management agent. Small values in the range produce small images; the minimum value produces the smallest possible image. Large values produce large images; the maximum value produces the largest possible image. Response of the mechanism to variation within the range must be repeatable and monotonic. Implementations will vary in the number of different levels that can be achieved within the range. This setting must be writable by management in a power state less than full power. The value must persist across power cycles."

6. Projector & Display Management WG 6 General Discussions - Resettable Counters and Replaceable FRUs Discussion on resettable counters in SNMP (Rick) – Do not let user write directly into counter property. – Add another property that acts like a function to reset the counter. Discussion on FRU replacements in SNMP MIB (Rick) – Similarly, add a property that functions to replace the unit. – Resets age counters, stores install date/time if available, increments replacement number, etc.

7. Projector & Display Management WG 7 Proposal: "Functional" Property to Reset Counter Behavior of a Counter object – Read: obtain the value of the counter – Write: error, not directly writable Add a ResetXxxCounter object for each resettable counter – Enumerated values: 1 = Reset counter to zero Any other value = do nothing – Read: value is zero – Write: Special value: reset the counter Any other value: do nothing

8. Projector & Display Management WG 8 Proposal: "Functional" Property to Replace FRU In any row that represents a Field Replaceable Unit, add several properties – Sequence counter of this unit: how many times has it been replaced? Incremented on every replacement Not writable, not resettable, never repeats – Time of last replacement Absolute date/time if we have it, sysUptime and power-on counter if we don't have date/time – Functional property used when the unit is replaced Increments the sequence counter Stores the new installation time Resets the age counter(s) and error counter(s) for this unit, if any

9. Projector & Display Management WG 9 General Discussions - Generating SNMP from XML Review of SNMP MIB generation status (Rick) – XSL translation of Properties, Tables, Textual Conventions for enumerated property values – Look at sample output Items that still need work – DefVal clause now required on SNMP objects If string length nonzero, must have a sensible value, e.g., "No description supplied" – Use Counter32 and Gauge32 But they cannot have ranges applied Use Integer32 for Gauge Remove ranges from Counters – Change concept of multiple tables in a group Causes problems writing Conformance clauses – May need to do SNMP V1 MIB also, some tools slow to adapt to V2

10. Projector & Display Management WG 10 Groups Should Contain Only One Table (Max) Restructure current groups that contain more than one table into separate groups.