Previous Table of Contents Next


1.5.2.3 Configuration Management

The standard says that configuration management “identifies, exercises control over, collects data from and provides data to open systems for the purpose of preparing for, initializing, starting, providing for the continuous operation of, and terminating interconnection services.” These services might include the collection of information regarding the system, alerts regarding system changes, and changes to the configuration of the system.

In the real world, the acronym MAC, which stands for moves, adds, and changes, typifies the management work. Networks are dynamic systems, and network administrators need to move personnel and rearrange their processing needs. This aspect of network management may be as simple as rearranging modular connectors at a wiring hub, or as complex as installing a LAN and its associated servers, communication circuits, and so on, at a remote location. Therefore, a significant aspect of the network management function involves keeping track of all these changes by using some type of database.

1.5.2.4 Performance Management

In the standard, performance management “enables the behavior of resources in the OSI environment and the effectiveness of communication activities to be evaluated.” These functions include gathering statistical and historical information and evaluating the system’s performance under a variety of real and hypothetical conditions.

Practically, performance management assures that the administrator satisfies the end users’ needs at all times. To do this, the administrator must select hardware and software systems according to the needs of the internetwork, then exercise these systems to their maximum potential. Performance and fault management are closely related, since you need to eliminate, or at least minimize, faults to obtain optimum performance. Many tools are available to measure performance. These include protocol analyzers, network monitoring software, and various utilities that come with the console programs of network operating systems.

1.5.2.5 Security Management

Academically, “the purpose of security management is to support the application of security policies by means of functions which include the creation, deletion, and control of security services and mechanisms; the distribution of security-relevant information; and the reporting of security related events.”

In other words, security protects the network. It defends against viruses, assures that remote and local users are authenticated, and installs encryption systems on any communication circuits that connect to a remote site.

1.6 The IEEE Network Management Architecture

The Institute of Electrical and Electronics Engineers (IEEE) is perhaps best known for developing the 802 series of LAN standards. These include specifications for Carrier Sense Multiple Access with Collision Detection (CSMA/CD) LANs such as 802.3 10BASE-T and 802.5 token-ring LANs. But the IEEE 802.1B LAN/MAN management standards are another key element of the IEEE work.

The IEEE Project 802 addresses the Physical and Data Link layers and extends into the higher layers of the architecture where appropriate. The IEEE LAN/MAN management standard uses ISO’s CMIP, which was discussed in Section 1.5, to extend into the higher layer. This architecture includes three elements (see Figure 1-10a): the LAN/MAN Management Service (LMMS), the LAN/MAN Management Protocol Entity (LMMPE), and the Convergence Protocol Entity (CPE). The LMMS defines the management service available to the LAN/MAN Management User (LMMU). The LMMPE communicates management information via protocol exchanges. LMMS and LMMPE use the ISO CMIS and CMIP standards and enable two LMMUs to exchange management information. The CPE allows LAN/MAN environments to provide LMMS. The CPE adds functions of reliable and sequential data delivery on top of the unacknowledged connectionless service provided by the IEEE 802.2 Logical Link Control (LLC) layer. The unacknowledged connectionless service is known as LLC Type 1.


Figure 1-10a.  LAN/MAN management communication architecture (©1992, IEEE)

Figure 1-10b illustrates the interaction between these network management operations. Several cooperative processes make up the request from a manager (an LMMU) to an agent (another LMMU). The manager’s LMMS communicates a request (REQ) using the LAN/MAN Management Protocol (LMMP). The agent receives this request as an indication (IND). The agent performs operations on the managed objects and then returns the results as a response (RSP). Finally, the LMMPE conveys the confirmation (CONF) to the manager.


Figure 1-10b.  LAN/MAN management information exchanges: operations (©1992, IEEE)

A managed object performs a similar series of steps to notify the manager of events (see Figure 1-10c). The managed object sends a notification to the agent, generating a request (REQ) at the LMMS. The LMMPE communicates that request across the LAN, yielding an indicate (IND) to the manager. Finally, the manager issues a response (RSP), which the agent receives as a Confirmation (CONF).


Figure 1-10c.  LAN/MAN management information exchanges: notifications (©1992, IEEE)

Figure 1-10d compares the IEEE architecture with the OSI model. The complexity of the two protocol stacks varies significantly. While CMIP uses all seven layers of the ISO model, the IEEE model runs CMIP and the CPE directly over the LLC layer—hence the acronym CMOL, which stands for CMIP over LLC. Because LLC provides connectionless service to the management application, some of the Association Control Service Element (ACSE) functions in the full CMIP stack are unnecessary. The CPE fills in and performs some, but not all, of the Network through Presentation layer functions. As Mary Jander’s article “Can CMOL Challenge SNMP” [1-8] notes, the benefit of the reduced CMOL stack is that it minimizes the memory requirements for agents. The disadvantage is that you cannot route CMOL across internetworks because it lacks Network layer functionality. This is not surprising, since CMOL was designed from a LAN and not an internetwork perspective.


Figure 1-10d.  Comparing CMIP and LMMP protocol stacks (©1992, IEEE)


Previous Table of Contents Next