1. doc.: IEEE 802.11-09/0491r0 Submission April 2009 Mark Hamilton, Polycom, Inc. Slide 1 MIB Attribute Types Date: 2009-04-27 Authors:

2. doc.: IEEE 802.11-09/0491r0 Submission April 2009 Mark Hamilton, Polycom, Inc. Slide 2 MIB background MIB is Management Information Base Purpose is to manage STAs and entities within STAs to allow proper and useful interoperation in a wireless network Such management is provided by interaction between entities to provide status and exert control –This is management interaction, not functional interaction provided by primitives –MIB attributes (a.k.a. “objects” or “variables”) provide an implicit interface between entities through read (“GET”) and write (“SET”) operations

3. doc.: IEEE 802.11-09/0491r0 Submission April 2009 Mark Hamilton, Polycom, Inc. Slide 3 MIB attribute usage guidelines Read and Write –One or more entities may read an attribute –At most one entity shall write an attribute (multiple writers creates interlock uncertainty) –The entity to which the attribute applies may or may not write it Static and Dynamic –Dynamic attributes can be written while STA in in operation, affecting management changes –Static attributes are not written during operation MIB attributes are not local variables –Attributes accessed solely within the entity do not provide any management function. They are an implementation issue to ensure the entity’s state-based behaviors conform to the Standard. –Such variables may be useful to describe behavior in the Standard, but are inappropriate in the MIB.

4. doc.: IEEE 802.11-09/0491r0 Submission April 2009 Mark Hamilton, Polycom, Inc. Slide 4 Types of MIB attributes Three types are used: –Capability: Static, initialized by entity as part of instantiation, read by other entities –Status: Dynamic, written by the entity to expose current conditions to reading entities –Control: Dynamic, written by another entity to control the applicable entity’s manageable behaviors The definition and described usage of each attribute should be clear about its type, and which entities use the interaction for read and write Dynamic attributes should have discussion about how and when changes are allowed/caused, and what the effect(s) of the change are

5. doc.: IEEE 802.11-09/0491r0 Submission April 2009 Mark Hamilton, Polycom, Inc. Slide 5 MIB attribute modification No more than one entity shall write (“SET”) a MIB attribute, to avoid mutex problems and other timing assumptions violations Every MIB attribute should be given careful consideration about how and when a write/update is allowed or caused, and the effects of the change. A MIB attribute whose change requires other actions, should be represented with a specific Management SAP primitive, instead of a MIB attribute. This allows the specification of actions that must be taken upon a change. –For example, if an Association must be re-established, or a BSS re- initialized

6. doc.: IEEE 802.11-09/0491r0 Submission April 2009 Mark Hamilton, Polycom, Inc. Slide 6 Derivation of attribute types Read by other entity(ies) Written by other entity(ies) Read by applicable entity CapabilityControl Written by applicable entity StatusNot used

7. doc.: IEEE 802.11-09/0491r0 Submission April 2009 Mark Hamilton, Polycom, Inc. Slide 7 Examples of types Capability – dot11CFPollable, dot11ManufacturerID, dot11XxxImplemented, dot11RadioMeasurementCapable, dot11ChannelAgilityPresent, dot11RRMMeasurementPilotCapability, dot11FTResourceRequestSupported, dot11ExtendedChannelSwitchEnabled Status – dot11XxxCount, dot11RadioMeasurementEnabled Control – dot11RTSThreshold, dot11ShortRetryLimit, dot11LongRetryLimit, dot11FragmentationThreshold, dot11PrivacyInvoked, dot11WEPDefaultKeyID, dot11CurrentFrequency, dot11RSNAConfigPairwiseCipherEnabled

8. doc.: IEEE 802.11-09/0491r0 Submission April 2009 Mark Hamilton, Polycom, Inc. Slide 8 Naming conventions To avoid confusion about type and purpose, name MIB attributes based on type: –Capability: dot11XxxImplemented –Status: dot11XxxCount, dot11XxxValue (statistics, etc.) –Status: dot11XxxActivated (capability that is enabled) –Control: dot11XxxThreshold, dot11XxxLimit, dot11XxxID Avoid names that leave writer entity ambiguous –dot11XxxEnabled

9. doc.: IEEE 802.11-09/0491r0 Submission April 2009 Mark Hamilton, Polycom, Inc. Slide 9 Local variables Variables that are not exposed outside an entity, for read or write Some example local variables – NAV, used_time, admitted_time, aXxxXxx (e.g. aSlotTime), CW, SSRC, SLRC Local variables should not be part of the MIB Recommend creating a separate Annex listing local variables, using a similar style and syntax to the MIB definitions, but making it clear that these are not accessible externally to the applicable entity. Especially useful if usage is not localized to a small section of the text. Some local variables could be used solely within the Standard’s text, if useful to clarify conforming behaviors, and don’t need formal defintion

10. doc.: IEEE 802.11-09/0491r0 Submission April 2009 Mark Hamilton, Polycom, Inc. Slide 10 Local variable naming conventions ???