Subject: Telecom Network Management

Topic: Network Management Applications.

Difficulty: Medium

Management Information trees:

• Managed objects are uniquely defined by a tree structure specified by the OSI model and are used in the Internet model.

• The objects in the MIT include network devices such as routers and hosts, virtual objects such as queues, filters, and events, and objects that Management information system (MIS) itself or applications create. A single global MIT provides a single naming scheme for all data.

• Figure5 shows the generic representation of the management information tree (MIT). There is a root node and well-defined nodes underneath each node at different levels.

• Each managed object occupies a node in the tree. In the OSI model, the managed objects are defined by a containment tree that represents the MIT.

• Figure6 shows the internationally adopted 051 MIT. The root node does not have an explicit designation.

• There are three nodes in the layer beneath the root: iso, ccitt (Itu), and iso-ccitt, (iso-itu).

• The Iso defines the International Standards Organization and itu defines the International Telecommunications Union (the old name is ccitt).

• The two standards organizations are on the first layer and define management of objects under them.

• The joint iso-itu node is for management objects jointly defined by the two organizations. The number in each circle identifies the designation of the object in each layer.

  

  

  Fig6: OSI Management Information Tree

• Thus, iso is designated as 1 and org as 1.3, dod (Department of Defense) as 13.6 and the Internet as 1.3.6.1.

• All Internet-managed objects will be that number followed by more dots and numbers. Names of the nodes are all in lowercase letters according to conventionASN.1.

• The definitions for managed objects are contained in ASN.1

• Language that specifies the management protocol in the application layer, which is transparent to the rest of the protocol layers, well-proven format is Abstract Syntax Notation One, ASN.1.

• ASN.1 is more than just syntax. It is a formal language developed jointly by CCITT (now ITU-T) and ISO for use with application layers for data transfer between systems.

• It is also applicable within the system for clearly separating the abstract syntax and the transfer syntax at the presentation layer.

• We define abstract syntax as the set of rules used to specify data types and structures for storage of information.

• Transfer syntax represents the set of rules for communicating information between systems. Thus, abstract syntax would be applicable to the information model and transfer syntax to the communication model.

• The abstract syntax can be used with any presentation syntax, depending on the medium of presentation. The abstract syntax in ASN.1 makes it independent of the lower-layer protocols.

• The algorithm to convert the textual ASN.1 syntax to machine-readable code is called basic encoding rules (BER).