Setting up the WMI SNMP Environment

Communicating with a network device using the WMI SNMP interface requires the configuration of the device, SNMP, and WMI services. The information in this topic explains how to set up the WMI SNMP environment.

The following sections are discussed in this topic:

The SNMP service is not enabled by default. You can enable the SNMP service and the WMI SNMP Provider through the Control Panel. Be aware that the SNMP service must be enabled and running for the WMI SNMP provider to work.

Starting with Windows Vista, use the following procedure to install the SNMP provider.

To install the SNMP Provider

1. From the Control Panel, select Programs.
2. Under Programs and Features, select Turn Windows features on or off.
3. In the Windows features list, scroll down to SNMP feature and expand the list so that you can see WMI SNMP Provider.
4. Select the check box for WMI SNMP Provider. The check box for SNMP feature is selected automatically because the provider requires SNMP.
5. Click OK.
6. From a command prompt or the Start menu, run Services.msc and ensure that the SNMP service is started.

An SNMP namespace defines a view of a network device.

The following procedure describes how to create an SNMP WMI namespace.

To create an SNMP namespace

1. Create an instance of the __Namespace system class either by compiling a Managed Object Format .mof file or by using the COM API for WMI.

   For more information, see Creating Hierarchies Within WMI.

2. Associate SNMP provider qualifiers with the namespace definition.

   The SNMP provider qualifiers contain implementation-specific context information and transport properties that define how the SNMP provider accesses an SNMP device. For more information, see Qualifiers Specific to the SNMP Provider.

3. Use the mofcomp command line tool to load the MOF code into the WMI repository.

   For more information, see Compiling MOF files.

The following MOF code example defines the \snmp namespace with a subset of the qualifiers that can be associated with an SNMP namespace.

// Load classes and instances into <\\.\root> namespace

#pragma namespace("\\\\.\\root")               

[ 
  AgentAddress( "localhost" ), 
  AgentReadCommunityName( "public"), 
  AgentWriteCommunityName( "private"), 
  AgentRetryCount( 1 ), 
  AgentRetryTimeout( 500 ), 
  AgentVarBindsPerPdu( 10 ),
  AgentFlowControlWindowSize ( 3 ) 
]

  instance of __Namespace
  {
      Name = "snmp" ;
  };

As a provider, the SNMP provider acts as a bridge between SNMP data and WMI classes. Therefore, you must have classes in WMI that represent different aspects of an SNMP-enabled device. To do so, you must use the SNMP information module compiler (smi2smir) to compile SNMP management information from the SNMP format into the equivalent CIM schema definitions. You can then direct the output of the information compiler into an SNMP schema database called the "SNMP Module Information Repository (SMIR)" or to several different kinds of MOF files.

The compiler runs in the command-line mode, using one MIB file as input. The following command loads the specified MIB file into the SMIR.

smi2smir /a <MIB file>

As a security measure, the SNMP "public" community is not created by default. You can create the community as described in Communities Registry Settings. If you do not have any community, then create the "public" community to access the SNMP provider.

The following commands are an example of how to generate MOF files from the MIB files that are installed when the SNMP provider is installed.

cd %windir%\system32\wbem\SNMP

Smi2smir /g ..\..\hostmib.mib > hostmib.mof

Smi2smir /g ..\..\ipforwd.mib > ipforwd.mof

Smi2smir /g ..\..\nipx.mib > nipx.mof

Smi2smir /g ..\..\mib_ii.mib > mib_ii.mof

Smi2smir /g ..\..\lmmib2.mib > lmmib2.mof

Smi2smir /g ..\..\mcastmib.mib > mcastmib.mof

Smi2smir /g ..\..\rfc2571.mib > rfc2571.mof

Smi2smir /g ..\..\wfospf.mib > wfospf.mof

Smi2smir /g ..\..\dhcp.mib..\..\msft.mib > dhcp.mof

Smi2smir /g ..\..\wins.mib..\..\msft.mib > wins.mof

Smi2smir /g ..\..\mipx.mib..\..\msft.mib > mipx.mof

Smi2smir /g ..\..\mripsap.mib..\..\msft.mib > mripsap.mof

Smi2smir /g ..\..\msipbtp.mib..\..\msft.mib > msipbtp.mof

Smi2smir /g ..\..\msiprip2.mib..\..\msft.mib > msiprip2.mof

The following commands are an example of how to add the MOF files that are generated from the MIB files to the WMI repository. If you want to add the MOF files to the list of files to be automatically restored in a WMI repository recovery, add the -AUTORECOVER flag to the end of each command. For more information about the WMI Mofcomp.exe command-line tool, see mofcomp.

mofcomp hostmib.mof

mofcomp ipforwd.mof

mofcomp nipx.mof

mofcomp mib_ii.mof

mofcomp lmmib2.mof

mofcomp mcastmib.mof

mofcomp rfc2571.mof

mofcomp wfospf.mof

mofcomp dhcp.mof

mofcomp mipx.mof

mofcomp mripsap.mof

mofcomp msipbtp.mof

mofcomp msiprip2.mof

Accessing SNMP Devices