SNMP MIB Modeling

1. 1 SNMP MIB Modeling J. Won-Ki Hong Dept. of Computer Science and Engineering POSTECH Tel: 054-279-2244 Email: jwkhong@postech.ac.kr

2. 2 Table of Contents SNMP MIB Object Modeling Categorize MIB Objects Translate Model into a MIB Modeling Example: Car

3. 3 SNMP MIB Modeling MIB is essential for developing and operating management systems SNMP MIBs are NOT object-oriented inheritance is not supported Analysis of MIB objects is required before writing MIB definitions Using the designed model, MIB definitions can be easily generated Similar to software engineering -- must design a system before any implementation!

4. 4 Step1: Categorize MIB Objects Components collections of logical & physical devices or services that are being managed Attributes fairly static properties of a modeled object Actions control a system Statistics useful information about what a system has been doing State the current condition of a system

5. 5 Components physical or logical containment relationships? what does it contain? start from the top level and work down until reasonable size is reached physical containment? e.g., a list of interface cards logical containments? e.g., communication systems Cardinality how many of an item are present in a system?

6. 6 Attributes the fairly static properties of the resource being modeled e.g., name, id, location, etc. can be refined into related groups Identity of an object determine ID by an attribute assign an arbitrary ID

7. 7 Actions SNMP does not support explicit action operation represented in terms of implicit actions which do their work through side effects this is achieved by setting some value of a MIB object Need to define action goals and action steps action goals? what does the manager need to be able to do to the managed resource? action steps? how does it do it?

8. 8 Statistics show a picture of the past a record of the interesting events which occurred since a specific point in time �high water marks� identify peaks in resource utilization all stats are considered valid for a specific period of time (known as epoch) What statistics are we interested in?

9. 9 State provides insight into the current condition of the resource represents dynamic properties of the resource stages of operation e.g., enabled/disabled resource usage level e.g., queue is 50% full a state graph (e.g., finite state machine) can be used to identify possible inputs and states of the resource

10. 10 Step2: Translate Model into MIB Generate an object analysis worksheet containing major components and their cardinality, attributes, statistics and states Translate the worksheet into MIB syntax sub-components with a cardinality greater than 0 should be part of a table stats representing increasing values are Counter type stats representing high or low water marks are Integer type states representing discrete stages of operation are enumerated Integer type states that have fluctuating values are Gauge type attributes of an object can be Octet String - human readable descriptions or binary data Integer - measurable quantities

11. 11 Modeling Example - CarPhysical Containments Engine compartment engine transmission climate control system Passenger compartment seats dashboard/instrument panel Chassis doors suspension system

12. 12 Modeling Example - CarLogical Containments Powertrain engine transmission Exhaust manifold muffler

13. 13 Modeling Example - CarAttributes Engine horsepower rating number of cylinders Powertrain drive type 2 or 4 wheel transmission type manual automatic # of speeds

14. 14 Modeling Example - CarActions Powertrain on/off engine shift the gear Exhaust release smoke

15. 15 Modeling Example - CarStatistics Engine peak horsepower highest RPMs total RPMs trip mileage total mileage

16. 16 Modeling Example - CarStates Engine stopped/starting/running/failed engine speed in RPMs oil pressure fuel consumption rate Powertrain drive engaged: 2 or 4 current gear

17. 17 Object Analysis Sheetfor Car Engine

18. 18 Engine MO Definition engCylTable OBJECT-TYPE SYNTAX SEQUENCE OF EngCylEntry ACCESS not-accessible STATUS mandatory DESCRIPTION �This table represents the sub-components of an engine that are dependent on the # of cylinders in the engine.� :: = { engine 1} engCylEntry OBJECT-TYPE SYNTAX EngCylEntry ACCESS not-accessible STATUS mandatory DESCRIPTION �A row in the engine cylinder table. Rows cannot be created or deleted via direct SNMP operations.� INDEX { engCylIndex } :: = { engCylTable 1}

19. 19 Engine MO Definition (cont�d) EngCylEntry ::= SEQUENCE { engCylIndex Unsigned32, -- table index engCylPistonSize Unsigned32, -- attributes engCylSparkPlugSize Unsigned32, engCylSparkPlugVendor OBJECT IDENTIFIER, engCylInjectorCapacity Unsigned32, engCylFuelConsumed Counter32, -- statistics engCylSparkPlugState INTEGER, -- states engCylSparkPlugSparkRate Gauge32, engCylInjectorState INTEGER, engCylInjectorFuelRate Gauge32, } Note that the definition for each object is further required.

20. 20 Summary Constructing a structure is the most critical part of MIB development Declaring the actual MIB objects is more of a task of translation than a labor or design Tools such as DMH MIB Compiler (www.dmhsoftware.com) and MG-Soft MIB Compiler (www.mg-soft.si) can be used to define and compile SNMP MIB definitions READING � David Perkins, Understanding SNMP MIBs, Prentice-Hall, Chapter 7