SNMP Representation of the Model

The SNMP agent supports an instance of the system group of MIB-II for identification and discovery purposes. In addition, it supports a logical representation physical system as defined by ENTITY-MIB (RFC 2737), and extended by the SUN-PLATFORM-MIB. The agent also supports multiple administrative views of this information that might be limited in some way.

Note - Many of the objects defined in the MIBs have a MAX-ACCESS of read-write, but these objects are only writable where such an operation is appropriate to the component being modeled. Currently, all instances are implemented as read-only.

The implementation of the agent defines the following MIB groups, which describe the physical and logical elements of the managed system.

The `entityPhysical` Group

The entityPhysical group describes the physical entities—identifiable physical resources managed by the agent (for example, chassis, power supplies, and sensors). These entities are represented by rows in the entPhysicalTable.

The `entityGeneral` Group

The entityGeneral group provides the last change time stamp for the time when any entity in the Physical Entity Table or Physical Mapping Table is changed.

The `entityMIBTraps` Group

The entityMIBTraps group defines the entConfigChange notifications used to signal a change to the last change time stamp.

Chapter 7 provides an overview of how the generic elements of SNMP represent the Sun platform SNMP model.

Physical Model

The Sun PSM physical model uses the ENTITY-MIB and SUN-PLATFORM-MIB to provide a containment hierarchy of hardware entities. Each entity is modeled as a separate row of the entPhysicalTable.

This information is presented using SNMP tables:

Physical Entity Table (entPhysicalTable)

This table provides a row per hardware entity. These rows are called entries and a particular row is referred to as an instance. Each entry contains:
- Physical class (entPhysicalClass)
- Common characteristics of the hardware entity
- Unique index (entPhysicalIndex)
- Unique name (entPhysicalName)
- Description (entPhysicalDescr)
- Reference (entPhysicalContainedIn) that points to the row of the hardware entity that acts as the container for this resource. This is zero for components, such as a chassis, that are not physically contained within another container.
Physical Mapping Table (entPhysicalContainsTable)

This table provides a virtual copy of the hierarchy of the hardware resources represented in the Physical Entity Table. This table is two-dimensional, indexed first by the entPhysicalIndex of the containing entry, and then by the entPhysicalIndex of each contained entry.

Classes

The entPhysicalClass is an enumerated value that provides an indication of the general hardware type of a particular physical entity, each of which is represented by a row in the entPhysicalTable.

The following list describes the set of entPhysicalClass elements:

other(1)

The enumeration other(1) applies if the physical entity cannot be classified by one of the following.
chassis(3)

The chassis class represents an overall container for equipment. Any class of physical entity can be contained within a chassis.
container(5)

The container class applies to a physical entity that can contain one or more removable physical entities, of the same or different type. For example, each empty or full slot in a chassis is modeled as a container. Field-replaceable units (FRUs), such as a power supply or fan, are modeled as modules within a container entity.
powerSupply(6)

The power supply class applies to a component that can supply power, such as a battery.
sensor(8)

The sensor class applies to a physical entity that is capable of measuring some physical property.
module(9)

The module class applies to a self-contained subsystem, and which is modeled within another physical entity such as a chassis or another module. The entity is always modeled within a container.

Logical Model

The logical model is not populated by this agent.

Event and Alarm Model

The ENTITY-MIB provides a single SNMP notification, entConfigChange, which signals a change to any of the tables in the MIB. It is set to provide a maximum of one trap every five seconds.

The SUN-PLATFORM-MIB defines more specific notifications and these are described in Chapter 11.

`SUN-PLATFORM-MIB`

The SUN-PLATFORM-MIB extends the Physical Entity Table to represent new classes of components.

Physical Model Table Extensions

The SUN-PLATFORM-MIB provides additional attributes from classes that are not represented in the Physical Entity Table. It extends the Physical Entity Table by adding the following sparsely populated table extensions:

Equipment Table Extension

This augments the Physical Entity Table to provide further information for managed objects of the Equipment class. This class is applicable for all Sun SNMP Management Agent hardware resources. Subclasses of the Equipment class are represented by further table extensions.
- Equipment Holder Table Extension
  
  This extends the Equipment Table Extension. It provides the additional information relevant for managed objects of the container(5) entPhysicalClass.
- Circuit Pack Table Extension
  
  This extends the Equipment Table Extension. It provides the additional information relevant for managed objects of the module(9) entPhysicalClass.
Sensor Table Extension

This extends the Equipment Table Extension. It provides the additional information relevant for managed objects of the entPhysicalClass sensor(8). Subclasses of the Sensor class are represented by further table extensions and identified by this table using sunPlatSensorClass.
- Binary Sensor Table Extension
  
  This extends the Sensor Table Extension. It provides additional information relevant for managed objects of the entPhysicalClass sensor(8) and sunPlatSensorClass binary(1).
- Numeric Sensor Table Extension
  
  This extends the Sensor Table Extension. It provides additional information relevant for managed objects of the entPhysicalClass sensor(8) and sunPlatSensorClass numeric(2).
- Discrete Sensor Table Extension
  
  This extends the Sensor Table Extension. It provides additional information relevant for managed objects of the entPhysicalClass sensor(8) and sunPlatSensorClass discrete(3).
Alarm Table Extension

This extends the Equipment Table Extension. It provides the additional information relevant for managed objects of the entPhysicalClass other(1) and sunPlatPhysicalClass alarm(8).
Power Supply Table Extension

This extends the Equipment Table Extension. It provides the additional information relevant for managed objects of the entPhysicalClass powerSupply(6).

Sun SNMP Management Agent MIBs