SMIv2-Structure of Management Information

The Structure of Management Information version 2(SMIv2) is component for network management. Its Functions are:

  1. To name Objects.
  2. To define the type of data that can be stored in an object.
  3. To show how to encode data for transmission over the network.

SMI is a guideline for SNMP. It emphasizes three attributes to handle an object: name, data type, and encoding method.


SMI requires that each managed object (such as a router, a variable in a router, a value, etc.) have a unique name. To name objects globally, SMI uses an object identifier, which is a hierarchical identifier based on a tree structure.

The tree structure starts with an unnamed root. Each object can be defined using a sequence of integers separated by dots. The tree structure can also define an object using a sequence of textual names separated by dots. The integer-dot representation is used in SNMP. The name-dot representation is used by people.

The image shows the same object with two different notations: <——–>

The objects that are used in SNMP are located under the mib-2 object, so their identifiers always start with


The second attribute of an object is the type of data stored in it. To define the data type, SMI uses fundamental Abstract Syntax Notation 1 (ASN.1) definitions and adds some new definitions. In other words, SMI is both a subset and a superset of ASN.1.

SMI has two broad categories of data type:


Simple Type – Simple Data Types are atomic data types. SOme of them are taken directly form ASN.1; some are added by SMI.
Structured Type – By combining simple and structured data types we can make new structured dat types. SMI defines two structured data types

  • SEQUENCE – A Sequence data type is a combination of simple data types, not necessarily of the same type. It is similar to the                                                  STRUCTURE used in C.
  • SEQUENCE OF – A Sequence of data type is a combination of simple data types all of the same type or combination of Sequence data                                           types all of same type. It is similar to ARRAY used in C.

I hope you have now understood what SMIv2 is and why, how, and where it is used.


About Abhijeet Deshpande

well I am a Computer engineer who likes to read about new technologies and also research about future technologies. I have created this blog for people who are interested in technology just like me and want to learn about them in detail. Also I am a automobile freak so you can expect some technologies related to them also on this blog. So as I have quoted "Its not just any other Technology related blog".

Posted on October 25, 2010, in Technology. Bookmark the permalink. Leave a comment.

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