Subject: Telecom Network Management
Topic: OSI Network Management
Subject: Telecom Network Management
Topic: OSI Network Management
Several network management standards are in use today. Table1 lists four standards and their salient points, and a fifth standard based on emerging technology. They are the OSI model, the Internet model, TMN, IEEE LAN/MAN, and Web-based management.
i. The Open System Interconnection (OSI) management standard is the standard adopted by the International Standards Organization (ISO).
ii. The OSI management protocol standard is Common Management Information Protocol (CMIP), and has built-in services, Common Management Information Service (CMIS), that specify the basic services needed to perform the various functions.
iii. It is the most comprehensive set of specifications, and addresses all seven layers of the OSI Reference Model.
iv. The specifications are object-oriented and hence managed objects are based on object classes and inheritance rules.
v. Besides specifying the management protocols, CMIP/CMIS also address the network management applications. Both LANs and WANs can be managed using CMIP/ CMIS.
vi. Two of the major drawbacks of the OSI management standard are that it is complex and that the CMIP stack is large. In contrast to CMIP, Simple Network Management Protocol (SNMP) is truly simple, as its name indicates.
vii. It started as an industry standard and has since become very much like the standard specifications of a standards-setting organization.
viii. The Internet Engineering Task Force (IETF) is responsible for all Internet specifications including network management. The managed objects are defined as scalar objects in SNMP, which was primarily intended to manage Internet components, but is now used to manage WAN and telecommunications systems.
ix. The Telecommunications Management Network (TMN) is designed to manage the telecommunications network and is oriented toward the needs of telecommunications service providers.
x. TMN is the standard of the International Telecommunication Union (ITO) and is based on OS1 CMIP/CMIS specifications. TMN extends the concept of management beyond managing networks and network components; its specifications address service and business considerations.
xi. The IEEE standards for LAN and MAN specifications are concerned only with OS1 layers 1 (physical) and 2 (data link), and they are structured similarly to OSI specifications.
xii. Both OSI/CMIP and Internet/SNMP protocols use IEEE standards for the lower layers. The IEEE 802.x series of specifications defines the standards for the various physical media and data link protocols.
xiii. IEEE 802.1 specifications present overview, architecture, and management. The IEEE 802.2 standard specifies the logical link control (LLC) layer. The other specifications in the IEEE series are for specific media and protocols. For example, 802.3 specifications are for Ethernet LANs.
xiv. The last category in Table is Web-based management, which is based on using Web technology, a Web server for the management system, and Web browsers for network management stations.
Table1: Network Management Standard
xv. The DMTF has chosen the Microsoft object-oriented management model, Common Information Model. JMX is based on a special subset of Java applets developed by Sun Microsystems that runs in the network components.
xvi. Network management is further complicated when the management system uses the new technology. The SNMP, based on scalar technology and simple definition of managed objects, was widely favored over CMIP.
xvii. With the need for a total management of network, service, and business for telecommunications service providers, TMN, which uses CMIP, is being revived.
xviii. CMIP, which was hard to implement because it required large memory and a better understanding of object-oriented technology, is now easier to implement.
xix. However, because of the numerous existing SNMP based agents, SNMP is also being explored for implementing TMN. Both SNMP and CMIP use polling methodology, which puts an additional load on the network. Besides, both require dedicated workstations for the network management system.
i. The OSI network model is an ISO standard and is the most superior of all the models; it is structured and it addresses all aspects of management.
ii. Figure1 shows an OSI network management architecture model that comprise four models: organization model, information model, communication model, and functional model.
iii. The organization model describes the components of a network management system, their functions, and their infrastructure. The organization model is defined in ISO- OSI Systems Management Overview. It defines the terms object, agent and manager.
OSI Network Management Model
iv. The ISO information model deals with the structure and organization of management information. ISO specifies the structure of management information (SMI) and the information database, Management Information Base (MIB). SMI describes how the management information is structured and MIB deals with the relationship and storage of management information.
v. The third model in OSI management is the communication model, which has three components: management application processes that function in the application layer, layer management between layers, and layer operation within the layers.
vi. The functional model is the fourth component of OSI management, and it deals with the user-oriented requirements of network management. OSI defines five functional application areas, namely, configuration, fault, performance, security, and accounting. These are defined as system management functions in OSI.
vii. Only OSI presents the complete model for network management; others deal with only a subset or are still in the process of developing standards.
viii. OSI deals with all seven networking layers. It lends itself to addressing service and business management, which is more than just networking.
ix. The second standard listed in Table1 is the SNMP/Internet standard. The IETF does not define architecture for the SNMP management model explicitly. However, it does exist implicitly.
x. The organization, information, and communication models are similar to OSI models. The SNMP network management model addresses the functional model in terms of operations, administration, and security.
xi. SNMP-based management is widely used for campus wide networks, although enterprise-wide networks are also managed by using distributed configurations of SNMP-based network management systems.
xii. The third standard in Table1 is Telecommunications Management Network (TMN), which is based on the OSI model. The focus of the TMN standard is toward managing telecommunications networks. Operations systems support service and business management.
xiii. The fourth standard in Table1 is the IEEE standard on management and is dedicated to the management of layers 1 and 2 of the OSI Reference Model.
xiv. It is applicable to LANs and MANs and addresses standards on broadband network management, which is of great relevance to the current technology.