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How to determine the correct OID Variable to track SNMP Data on ScreenOS

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Trying to query specific SNMP Data to plot on an MRTG graph by specifying OID variable


When attempting an snmpget on an OID, receive the following error from the SNMP manager: 

No Such Object available on this agent when attempting a snmpget


The way to determine which OID variable to use for custom enterprise MIB variables is to inspect the individual enterprise MIB files.  Based on this, you can determine which OID variable to assign for your snmpget.

Example:  Trying to track the OID variable for number of allocated sessions.

  1. Download the MIB files for the specific ScreenOS you are running.  See KB4233 - Where Do I Download MIB Files?

  2. Open the file "NS-SMI.mib".  From this file, notice the NetScreen object identifier is enterprise 3224.  This is the enterprise tree you will use for the NetScreen private mib.
    netscreen OBJECT IDENTIFIER ::= { enterprises 3224 }  -- used for Netscreen SysObject ID
  3. For tracking number of sessions allocated, look for the resource identifier in the NS-SMI.mib file.
    netscreenResource OBJECT IDENTIFIER ::= { netscreen 16 }
  4. From this, start the snmp get on .iso.
  5. Open the file "NS-RES.mib".  Do a find for "allocate session".  You will see the following excerpt from the NS-RES.mib file:

    nsResSession OBJECT IDENTIFIER ::= { netscreenResource 3 }

    nsResSessAllocate OBJECT-TYPE
        SYNTAX        Integer32
        MAX-ACCESS    read-only
        STATUS        current
            "Allocate session number."
        ::= { nsResSession 2 }
  6. Now, specify .3.2, for the nsResSession object identifier, and the nsResSessAllocate object type.

The OID variable for the snmpget is .iso.  Issuing an snmpget on .sio., you will give the error message "object not found".  Not all OID variables in the tree are used by ScreenOS.

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