9/24/12

Introduction to Network Management Framework

The Internet-Standard Management Framework consists of four major parts:

  • Definitions of network management objects, known as MIB objects,
  • A data definition language, known as SMI (Structure of Management Information),
  • A protocol, SNMP. For conveying information and commands between a managing entity and an agent executing on behalf of that entitity within management network device,
  • Security and administration capabilities.


SMI defines the data types, and object model, and rules for writing and revising management information. MIB objects are specified in this data definition language. SMI is based on ASN.1 (Abstract Syntax Notation One), abstraction over machine-dependent representation of data.

MIB, or Management Information Base, can be thought of as a virtual information store, holding management objects whose values collectively reflect the current "state" of the network. These values may be queried and/or set by a managing entity by sending SNMP messages to the agent that is executing in a managed device on behalf of managing entity.

SNMP, or Simple Network Management Protocol is used to convey MIB information among managing entities and agents executing on behalf of managing entities. The most common usage of SNMP is in a request-response mode. A second common usage of SNMP is for an agent to send unsolicited message, known as trap message, to a managing entity. Trap messages are used to notify a managing entity of an exceptional situation that has resulted in changes to MIB object values. Network administrator might want to receive a trap message, for example when an interface goes down, congestion reaches a predefined level on a link, or some other noteworthy event occurs.

Security : SNMPv3 (Simple Network Management Protocol version 3) security is known as user-based security in that there is traditional concept of user, identified by a username, with which security information such as a password, key value, or access privileges are associated. SNMPv3 provides for encryption, protection against playback attacks and access control.

Management Capabilities can be added by writing management application (or using existing software) that lets managing entity to "monitor, test, poll, configure, analyze, evaluate, and control the network and element resources to meet the real-time, operational performance and Quality of Service requriements at a reasonable cost".

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