SmartMIB Professional Solution:

MIB EXPRESSIONs and MIB EVENTs Wizards

(SM-ProPlus-EXP&EVNT)

MIB Expressions Wizard:

There is always a need for creating new, customized MIB objects for monitoring. Such needs vary from one management philosophy to another.

Rather than fill more and more MIBs with standardized objects, the Expression MIB supports externally defined expressions of existing MIB objects. The result of such expression is the creation of a new Custom-Defined MIB Objects that can be treated like any other MIB Objects residing in the SNMP Agent of the particular device.

This Process provides a procedure to create expressions on the network devices supporting the industry standard EXPRESSION-MIB. Steps to build a MIB Expression on either the desktop or the Web based wizard are introduced below:

To start the Web wizard, then the user needs to enter the smartmib_server/smartmib  (smartmib server name or IP address in the URL) as below then entering the User name and password. It is important to note that at initial installation the default user name is ‘administrator’ with an empty password.

To start the MIB expression wizard; choose the MIB Expression item under the Wizards menu option then click on ‘Start’ as below.

Step 1)           Selecting the Network Device

In this step the Inventory list of the devices where the particular expression is to be evaluated is selected.

        DEFINE DEV    DISPL;

        Input( COMBO-CTRL,

                "Selecting the Event Trigger Network Device",

                "MIB Expression Wizard", DEV,

                " BrusselsDevice", " London_router", " TokyoOffice");

Similarly from the Web wizard;

Step 2)           Setting the MIB Expression Name

This step is used to specify the MIB Expression Name; it is needed to create the named entry in the expNameTable first to create an expression.

        DEFINE ExpVariable   DISPL;

        Input( TEXT-CTRL,

                "Expression Name",

                "MIB Expression Wizard", ExpVariable         );

          Note:

        This name should be unique from one expression to the other.

        Setting the name above as ‘exp’ è ASCII: 101.120.112

Similarly from the Web wizard;

It is important next to learn the expNameHighestIndex value to make sure that this wizard process uses the next available expExpressionIndex. This could be done by simply adding a 1 to the value of expNameHighestIndex:

        DEFINE IndexVar       INT;

        IndexVar = POLL (expNameHighestIndex); 

        IndexVar = IndexVar + 1;

Then; setting the identification number used for identifying the expression:

        SET(DEV, expExpressionIndex IndexVar, 101.120.112);

Followed by Clearing out any previous entries and starting the building of the row:

        SET(DEV, expNameStatus 6, 101.120.112);

        SET(DEV, expNameStatus 5, 101.120.112);

Now that an entry has already been created in the expNameTable, this automatically creates an entry in the expExpressionTable.

Step 3)           Setting the Expression Value Type

In this step, the wizard prompts the administrator to set the evaluated expression’s SNMP MIB Object value Data-Type.

        Input( COMBO-CTRL,

                "Expression Value Type",

                "MIB Expression Wizard", ExpVariable,

                "1:counter32", "2:unsignedOrGauge32", "3:timeTicks");

Similarly from the Web wizard;

Possible values for expExpressionValueType are:

        1:counter32     (default)

        2:unsignedOrGauge32
          3:timeTicks
          4:integer32
          5:ipAddress
          6:octetString
          7:objectId
          8:counter64

The associated SET command should look something like below:

        SET(DEV, expExpressionValueType 2, expExpressionIndexVar);

Step 3)           Setting the Expression Comment

This step is used to specify the MIB Expression Comment.

        Input( TEXT-CTRL,

                "Expression Comment",

                "MIB Expression Wizard", ExpVariable);

Similarly from the Web wizard;

Note:

The default expression value specifying the type of the MIB Object resultant value obtained from the expression is “Counter32”.

The associated SET command to set the expression comment is as follows:

SET(DEV, expExpressionComment "new expression", expExpressionIndexVar);

Step 4)           Setting the Expression Formula

This step is used to specify the MIB Expression that needs to be evaluated.

        Input( TEXT-CTRL,

                "Expression Formula",

                "MIB Expression Wizard", ExpVariable);

Similarly from the Web wizard;

Note:

The expression Formula to be evaluated. The only allowed operators are:

                   ( )
                   - (unary)
                   + - * / %
                   & | ^ << >> ~
                   ! && || == != > >= < <=

        SET(DEV, expExpression '$1 - $2', expExpressionIndexVar);

Step 4)           Specifying the expression Object Identifier

This step is used to specify the MIB Expression Object Identifier.

        Input( COMBO-CTRL,

                "Expression Object Identifier",

                "MIB Expression Wizard", ExpVariable,

                "ifSpeed", "ifInOctets", "ifOutOctets");

Similarly from the Web wizard;

Note:

The expression’s Object identifiers may or may NOT be fully qualified. If its not fully qualified; then the Object’s Wild Card should be set.

Step 5)           Setting the Expression Object Sampling Type

This step is used to specify the MIB Expression Object Sampling Type.

        Input( COMBO-CTRL,

                "Expression Object Sampling Type",

                "MIB Expression Wizard", ExpVariable,

                "absoluteValue", "deltaValue");

Similarly from the Web wizard;

Note:

The expression Object Sampling method is either an ‘AbsoluteValue’ representing the current Object value or a ‘DeltaValue’ representing the difference between two concurrent instances of the Object.

expObjectSampleType possible values are:

        1 : absoluteValue

          2 : deltaValue

        SET(DEV, expObjectSampleType 1, expExpressionIndexVar.1);

        SET(DEV, expObjectSampleType 1, expExpressionIndexVar.2);

Step 6)           Setting the Expression Wild Card Setting

Specifying whether the expObjectID is wild carded or not.

        Input( COMBO-CTRL,

                "Expression Object Wild Card Setting",

                "MIB Expression Wizard", ExpVariable,

                "true", "false");

Similarly from the Web wizard;

Note:

The expression Object Wild Card setting depends on the expression instancing; if its NOT fully instanced, the Object wildcard should be set to “True”.

expObjectIDWildcard possible values are:

        1:true

        2:false

The corresponding expObjectIDWildcard SET command is as below:

        SET(DEV, expObjectIDWildcard 1, expExpressionIndexVar.1);

Final Step)    Activating the EXPRESSION

This is done by setting the new Expression’s Object and Name statuses to Active.

        SET(DEV, expObjectStatus 1,         expExpressionIndexVar.1);

        SET(DEV, expNameStatus 1,          101.120.112);

The value of the expression can now be obtained from the expValueTable.

Note:

In the Expression MIB the results of an evaluated expression are custom-defined MIB objects that can be used like any other MIB objects. For example, they can be used by a management application directly or referenced from another MIB, such as the Event MIB. They can even be used by the Expression MIB itself, forming expressions of expressions.

From the Web wizard however; a process and an associated process name are created and listed in the appropriate processes list to be started later by the administrator.

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