Discovery: identifying the device [SNMP MP Chap 2] #sysctr #scom

Update

My first device discovery method implied a new SNMP GET to be able to identify the device, as my fellow MVP Alexey Zhuravlev pointed out it’s not necessary. Since the OID is already discovered by the standard OpsMgr discovery we just need to iterate through the discovered device and get our own device from the existing OID. Thanks Alex for pointing this out and making me feel like an idiot ;-).

In any case I will keep the old discovery method for future reference at the bottom of the article.

Identifying the device

The very first step to monitor a generic device is to get a unique identifier for the device itself. This is important since we need to discover the device in order to apply the proper monitoring policies. The first id to check for is sysObjectID (.1.3.6.1.2.1.1.2), the id is returned by OpsMgr discovery itself.

The easy way is to add the generic device IP to our discovery rule and let Operations Manager to perform the basic discovery, if this doesn’t work it’s useless to go forward, the device needs to be discovered by standard Operations manager discovery before we can do anything with it. Once it has been discovered we just need to step in the administration space and, under network devices, select the properties of the device:

 There are obviously other methods to get to this OID for example snmpwalk from SharpSnmpLib can be used (see references in chapter 1), for an SNMP v2 device the syntax is something like this:

snmpget -v=2 -c=public localhost .1.3.6.1.2.1.1.2

where “localhost” must be substituted with the device IP and the community set accordingly, but this is more a troubleshooting technique then something useful at this stage: remember the device must be first discovered by Operations Manager.

Discovering the device

One we have the the device id we can write our discovery. To do this:

1.       We must define a new class derived by System.NetworkManagement.Node. If our device is a switch we can use the System.NetworkManagement.Switch class as well. What if it is a router, easy System.NetworkManagement.Router.

QND.MyNetwork.Device class

    <EntityTypes>

      <ClassTypes>

        <!– In this section, modify the attributes based on your needs. Ensure the

             Base attribute matches the application you are modeling.

             More information can be found in the Management Pack Development Kit:

             http://msdn.microsoft.com/en-us/library/ee533867.aspx –>

        <ClassType ID=“QND.MyNetwork.Device“ Accessibility=“Public“ Abstract=“false“ Base=“Network!System.NetworkManagement.Node“ Hosted=“false“ Singleton=“false“ Extension=“false” />

        </ClassType>

</EntityTypes>

 

2.       Let’s define the discovery datasource. We just use the FilteredClassSnapshotDataMapper to get our device

XML

<DataSourceModuleType ID=“QND.MyNetwork.Device.Discovery.DS“ Accessibility=“Internal“ Batching=“false“>

        <Configuration>

          <xsd:element minOccurs=“1“ name=“IntervalSeconds“ type=“xsd:integer“ />

          <xsd:element minOccurs=“0“ name=“SyncTime“ type=“xsd:string“ />

          <xsd:element minOccurs=“0“ maxOccurs=“1“ name=“Version“ type=“xsd:string“ />

          <xsd:element name=“DisplayName“ type=“xsd:string“ />

          <xsd:element name=“Model“ type=“xsd:string“ />

        </Configuration>

        <OverrideableParameters>

          <OverrideableParameter ID=“IntervalSeconds“ ParameterType=“int“ Selector=“$Config/IntervalSeconds“/>

          <OverrideableParameter ID=“SyncTime“ ParameterType=“string“ Selector=“$Config/SyncTime“/>

        </OverrideableParameters>

        <ModuleImplementation Isolation=“Any“>

          <Composite>

            <MemberModules>

              <DataSource ID=“Scheduler“ TypeID=“System!System.Discovery.Scheduler“>

                <Scheduler>

                  <SimpleReccuringSchedule>

                    <Interval>$Config/IntervalSeconds$</Interval>

                    <SyncTime>$Config/SyncTime$</SyncTime>

                  </SimpleReccuringSchedule>

                  <ExcludeDates />

                </Scheduler>

              </DataSource>

              <ConditionDetection ID=“MapToDiscovery“ TypeID=“System!System.Discovery.FilteredClassSnapshotDataMapper“>

                <Expression>

                  <SimpleExpression>

                    <ValueExpression>

                      <Value>$Target/Property[Type=”Network!System.NetworkManagement.Node”]/SystemObjectID$</Value>

                    </ValueExpression>

                    <Operator>Equal</Operator>

                    <ValueExpression>

                      <Value Type=“String“>.1.3.6.1.4.1.41091.1.1</Value>

                    </ValueExpression>

                  </SimpleExpression>

                </Expression>               

                <ClassId>$MPElement[Name=’QND.MyNetwork.Device’]$</ClassId>

                <InstanceSettings>

                  <Settings>

                    <Setting>

                      <Name>$MPElement[Name=’System!System.Entity’]/DisplayName$</Name>

                      <Value>$Config/DisplayName$</Value>

                    </Setting>

                    <Setting>

                      <Name>$MPElement[Name=’Network!System.NetworkManagement.Node’]/DeviceKey$</Name>

                      <Value>$Target/Property[Type=”Network!System.NetworkManagement.Node”]/DeviceKey$</Value>

                    </Setting>

                    <Setting>

                      <Name>$MPElement[Name=’Network!System.NetworkManagement.Node’]/Model$</Name>

                      <Value>$Config/Model$</Value>

                    </Setting>

                    <Setting>

                      <Name>$MPElement[Name=’Network!System.NetworkManagement.Node’]/Vendor$</Name>

                      <Value>QND</Value>

                    </Setting>

                    <Setting>

                  </Settings>

                </InstanceSettings>

              </ConditionDetection>

            </MemberModules>

            <Composition>

              <Node ID=“MapToDiscovery“>

                <Node ID=“Scheduler“ />

              </Node>

            </Composition>

          </Composite>

        </ModuleImplementation>

        <OutputType>System!System.Discovery.Data</OutputType>

      </DataSourceModuleType>

 

3.       Finally we must define our discovery rule targeted at the generic System.Network.Node class

MyNetwork.Device discovery rule

  <Discovery ID="QND.MyNetwork.Device.Discovery" Enabled="true" ConfirmDelivery="false" Remotable="true" Priority="Normal" Target="Network!System.NetworkManagement.Node">

    <Category>Discovery</Category>

    <DiscoveryTypes>

      <DiscoveryClass TypeID="QND.MyNetwork.Device" />

    </DiscoveryTypes>

    <DataSource ID="DS" TypeID="QND.MyNetwork.Device.Discovery.DS">

      <IntervalSeconds>43200</IntervalSeconds>

      <SyncTime />

      <DisplayName>$Target/Property[Type="Network!System.NetworkManagement.Node"]/sysName$</DisplayName>

      <Model>MyNetwork Device Model XYZ</Model>

    </DataSource>

  </Discovery>

 

This is it. But let’s review the key points here to make this process really generic. The QND.MyNetwork.Device.Discovery.DS is a composition of a standard scheduler and a filtered snapshot class data mapper. The filter is used to actually filter our device by sysObjectID. Basically this module, at the scheduled time, enumerates all the NetworkNode discovered devices and maps the ones with the corresponding sysObjexctID to our device class. All this is done without any network traffic.

From here we can go on building our specific monitor, but this is the topic for another post.

The Old way

The following is the old discovery data source, it basically gets the system object ID via SNMP, this is not needed since OpsMgr already discovered it for us.

4.       Using the System.NetworkManagement.SnmpProbe we must define a new data source module type to feed our discovery rule. To make code reusable I will define a generic datasource that does the match and a specific datasource that perform the actual mapping

Generic datasource to match on device sysObjectID

  <DataSourceModuleType ID="QND.NetLibrary.MatchOID.DS" Accessibility="Public" Batching="false">

    <Configuration>

      <IncludeSchemaTypes>

        <SchemaType>System!System.ExpressionEvaluatorSchema</SchemaType>

        <SchemaType>Snmp!System.SnmpVarBindsSchema</SchemaType>

      </IncludeSchemaTypes>

      <xsd:element minOccurs="1" name="IntervalSeconds" type="xsd:integer" />

      <xsd:element minOccurs="0" name="SyncTime" type="xsd:string" />

      <xsd:element minOccurs="0" maxOccurs="1" name="NoOfRetries" type="xsd:unsignedInt" default="3" />

      <xsd:element minOccurs="0" maxOccurs="1" name="Timeout " type="xsd:unsignedInt" default="500" />

      <xsd:element minOccurs="0" maxOccurs="1" name="Port" type="xsd:unsignedInt" default="161" />

      <xsd:element name="IP" type="xsd:string" />

      <xsd:element name="CommunityString" type="xsd:string" />

      <xsd:element minOccurs="0" maxOccurs="1" name="Version" type="xsd:string" />

      <xsd:element name="ObjectOID" type="xsd:string" />

    </Configuration>

    <ModuleImplementation Isolation="Any">

      <Composite>

        <MemberModules>

          <DataSource ID="Scheduler" TypeID="System!System.Discovery.Scheduler">

            <Scheduler>

              <SimpleReccuringSchedule>

                <Interval>$Config/IntervalSeconds$</Interval>

                <SyncTime>$Config/SyncTime$</SyncTime>

              </SimpleReccuringSchedule>

              <ExcludeDates />

            </Scheduler>

          </DataSource>

          <ProbeAction ID="Probe" TypeID="Network!System.NetworkManagement.SnmpProbe">

            <Walk>false</Walk>

            <WalkReturnMultipleItems>false</WalkReturnMultipleItems>

            <NoOfRetries>3</NoOfRetries>

            <Timeout>500</Timeout>

            <Port>$Config/Port$</Port>

            <SNMPv3UserName>$RunAs[Name="Network!System.NetworkManagement.SnmpV3.MonitoringAccount"]/UserName$</SNMPv3UserName>

            <SNMPv3AuthProtocol>$RunAs[Name="Network!System.NetworkManagement.SnmpV3.MonitoringAccount"]/AuthenticationProtocol$</SNMPv3AuthProtocol>

            <SNMPv3AuthPassword>$RunAs[Name="Network!System.NetworkManagement.SnmpV3.MonitoringAccount"]/AuthenticationKey$</SNMPv3AuthPassword>

            <SNMPv3PrivProtocol>$RunAs[Name="Network!System.NetworkManagement.SnmpV3.MonitoringAccount"]/PrivacyProtocol$</SNMPv3PrivProtocol>

            <SNMPv3PrivPassword>$RunAs[Name="Network!System.NetworkManagement.SnmpV3.MonitoringAccount"]/PrivacyKey$</SNMPv3PrivPassword>

            <SNMPv3ContextName>$RunAs[Name="Network!System.NetworkManagement.SnmpV3.MonitoringAccount"]/ContextName$</SNMPv3ContextName>

            <IsWriteAction>false</IsWriteAction>

            <IP>$Config/IP$</IP>

            <CommunityString>$Config/CommunityString$</CommunityString>

            <Version>$Config/Version$</Version>

            <SnmpVarBinds>

              <SnmpVarBind>

                <OID>.1.3.6.1.2.1.1.2.0</OID>

                <Syntax>0</Syntax>

                <Value VariantType="8" />

              </SnmpVarBind>

            </SnmpVarBinds>

            <OutputOnError>false</OutputOnError>

          </ProbeAction>

          <ConditionDetection ID="FilterOnObjectID" TypeID="System!System.ExpressionFilter">

            <Expression>

              <SimpleExpression>

                <ValueExpression>

                  <XPathQuery Type="String">SnmpVarBinds/SnmpVarBind[OID=".1.3.6.1.2.1.1.2.0"]/Value</XPathQuery>

                </ValueExpression>

                <Operator>Equal</Operator>

                <ValueExpression>

                  <Value Type="String">$Config/ObjectOID$</Value>

                </ValueExpression>

              </SimpleExpression>

            </Expression>

          </ConditionDetection>

        </MemberModules>

        <Composition>

          <Node ID="FilterOnObjectID">

            <Node ID="Probe">

              <Node ID="Scheduler" />

            </Node>

          </Node>

        </Composition>

      </Composite>

    </ModuleImplementation>

    <OutputType>Snmp!System.SnmpData</OutputType>

  </DataSourceModuleType>

 

Specific discovery datasource for QND.MyNetwork.Device

  <DataSourceModuleType ID="QND.MyNetwork.Device.Discovery.DS" Accessibility="Internal" Batching="false">

  <Configuration>

    <xsd:element minOccurs="1" name="IntervalSeconds" type="xsd:integer" />

    <xsd:element minOccurs="0" name="SyncTime" type="xsd:string" />

    <xsd:element minOccurs="0" maxOccurs="1" name="NoOfRetries" type="xsd:unsignedInt" default="3" />

    <xsd:element minOccurs="0" maxOccurs="1" name="Timeout " type="xsd:unsignedInt" default="500" />

    <xsd:element minOccurs="0" maxOccurs="1" name="Port" type="xsd:unsignedInt" default="161" />

    <xsd:element name="IP" type="xsd:string" />

    <xsd:element name="CommunityString" type="xsd:string" />

    <xsd:element minOccurs="0" maxOccurs="1" name="Version" type="xsd:string" />

    <xsd:element name="DisplayName" type="xsd:string" />

    <xsd:element minOccurs="1" name="DeviceKey" type="xsd:string" />

    <xsd:element name="Model" type="xsd:string" />

    <xsd:element name="Vendor" type="xsd:string" />

  </Configuration>

  <ModuleImplementation Isolation="Any">

    <Composite>

      <MemberModules>

        <DataSource ID="Seed" TypeID="QND.NetLibrary.MatchOID.DS">

          <IntervalSeconds>$Config/IntervalSeconds$</IntervalSeconds>

          <SyncTime>$Config/SyncTime$</SyncTime>

          <Port>$Config/Port$</Port>

          <IP>$Config/IP$</IP>

          <CommunityString>$Config/CommunityString$</CommunityString>

          <Version>$Config/Version$</Version>

          <ObjectOID>.1.3.6.1.4.1.41091.1.1</ObjectOID>

        </DataSource>

        <ConditionDetection ID="MapToDiscovery" TypeID="System!System.Discovery.ClassSnapshotDataMapper">

          <ClassId>$MPElement[Name='QND.MyNetwork.Device']$</ClassId>

          <InstanceSettings>

            <Settings>

              <Setting>

                <Name>$MPElement[Name='System!System.Entity']/DisplayName$</Name>

                <Value>$Config/DisplayName$</Value>

              </Setting>

              <Setting>

                <Name>$MPElement[Name='Network!System.NetworkManagement.Node']/DeviceKey$</Name>

                <Value>$Config/DeviceKey$</Value>

              </Setting>

              <Setting>

                <Name>$MPElement[Name='Network!System.NetworkManagement.Node']/Model$</Name>

                <Value>$Config/Model$</Value>

              </Setting>

              <Setting>

                <Name>$MPElement[Name='Network!System.NetworkManagement.Node']/Vendor$</Name>

                <Value>$Config/Vendor$</Value>

              </Setting>

            </Settings>

          </InstanceSettings>

        </ConditionDetection>

      </MemberModules>

      <Composition>

        <Node ID="MapToDiscovery">

          <Node ID="Seed" />

        </Node>

      </Composition>

    </Composite>

  </ModuleImplementation>

  <OutputType>System!System.Discovery.Data</OutputType>

</DataSourceModuleType>

 

But let’s review the key points here to make this process really generic. The QND.NetLibrary.MatchOID.DS is a composition of a standard scheduler, with the generic SNMP probe configured to SNMP GET (<Walk>false</Walk>) the RFC standard sysObjectID, the result is filtered to return just the devices with a matching OID ($Config/ObjectOID$). It can be underlined the isolation of SNMPv3 parameters, since it’s highly improbable we will use different credentials when running our workflows from the credential used to discover the device. This will make our subsequent workflows easier to read. This is a generic module that, if this series will continue, will add to a generic Network Library management pack.

The actual discovery datasource builds on the QND.NetLibrary.MatchOID.DS sets the OID to be matched and maps the resulting SNMP data to the QND.MyNetwork.Device class. As you can read this is where we can add some more data to the discovered properties (for example the model information). The mapping is done using a standard System.Discovery.ClassSnapshotDataMapper.

Finally the actual discovery rule, this rule will hit every single network device discovered so far so I would suggest to schedule it once or twice a day, for every device it will perform a SNMP GET and check if the returned OID is the MyNetwork.Device one, if so the device is discovered.

 

– Daniele

This posting is provided “AS IS” with no warranties, and confers no rights.