How the SNMP Adapter for WBEM Works

The Solaris operating environment initializes WBEM Services before starting the Solstice Enterprise Agents Master Agent. By default, the SNMP Adapter for WBEM, or Adapter, is disabled. However, once you enable the Adapter, the Solstice Enterprise Agents Master Agent (snmpdx) starts the Adapter automatically. The Adapter is described in snmpXwbemd(1M).

An SNMP Manager passes an SNMP Get-request to the Solstice Enterprise Agents Master Agent. The Master Agent then sends the Get-request to the Adapter, which uses the mapping files in /var/sadm/wbem/snmp/map to translate the objects in the Get-request into corresponding CIM objects. The Adapter also translates the CIM objects into SNMP objects in a Get-response.

At present, only Get-request and scalar objects are supported in Solaris 9. Get-next-request, Get-bulk-request, and Set-request as well as other objects are not currently supported.

The Adapter searches this directory alphabetically for the first file to which the extension .map is appended. The Adapter then reads all mapping files in the directory and caches their contents. The Adapter uses the contents of these files to translate the objects that are specified in the Get-request into corresponding CIM objects. The Adapter subsequently ignores duplicate OIDs in the mapping files in the directory. For example, if this OID appears in 002SUNWlvma.map:

1.3.6.1.2.1.1.1.0 My_ComputerSystem Description SnmpString

and the same OID appears in 050SUNWwbcou.map, which the Adapter reads after 002SUNWlvma.map:

1.3.6.1.2.1.1.1.0 Solaris_ComputerSystem Description SnmpString

then the Adapter ignores the OID that is specified in 050SUNWwbcou.map.

The Adapter subsequently generates a Get-response for each Get-request that an SNMP Manager submits. If the Adapter cannot find a corresponding entry in any mapping file, the Adapter returns a Get-response error.

How the Master Agent Routes a Request: SNMP Adapter for WBEM Compared to the Sun SNMP Agent

Until the release of the SNMP Adapter for WBEM, when an SNMP Manager sent a Get-request for an SNMP MIB-2 variable to the Solstice Enterprise Agents Master Agent, the Master Agent routed the request to the Sun SNMP MIB-2 Agent (mibiisa). Because the Adapter also handles SNMP MIB-2 requests, what happens if the Sun SNMP Agent and the SNMP Adapter for WBEM are both running at the same time? How does the Master Agent route a request?

The Master Agent builds a node table based on the subtrees that are defined in each subagent registration file. The mibiisa subagent registers the entire MIB-2 subtree and the Sun Microsystems MIB subtree. The Adapter registers the MIB-2.system subtree and the hostRsrc subtree. The Master Agent does not allow two agents to register the same subtree.

The Sun SNMP MIB-2 Agent is described in mibiisa(1M). The Master Agent is described in the Solstice Enterprise Agents 1.0 User Guide.

At initialization, the Master Agent creates a node table that contains each subtree that is registered. The Master Agent forwards each Get-request to the agent whose subtree best matches the OID that is included in the request. A request for mib-2.system.5.0, for example, is forwarded to the Adapter. A request for mib-2.interfaces.1.0, on the other hand, is forwarded to the mibiisa subagent. If the OID is not defined within any subtree that is registered by the Master Agent, the Master Agent returns an error in the Get-response.

The SNMP Adapter for WBEM supports SNMP V1 requests only.