DTJ Number 3 September 1987 - Digital Technical Journals

Mark W. Sylor 1The NMCC/DECnetMonitor DesignThe NMCCjDECnet Monitor system allows the monitoring of a .DECnetnetwork. Using the monitor at a central point allows the network managerto control the operation of the network. To be effective, e needsinfonnation about the network's current configuration, state, I performance,and errors. The monitor maintains and interprets a dat base ofnetwork infonnation, which is presented clearly and concisely to theuser through interactive graphics and other techniques. The interpretationand evaluation techniques analyze situations that may be problemsand alert the user to them in a real-time operation.Network management can be described as a controland feedback loop like the one shown in Figure1. In this loop, information is gathered fromthe network by the monitor function and presentedto the network manager. He then decidesif the situation in the network is satisfactory ornot. If not, the manager can initiate some controlaction - perhaps issue a correction, gather furtherinformation, or perform a test. The controlloop feedback cycle is "Look, Think, Act."It's clear that one key to network managementis the manager's having available the informationhe needs to make control decisions. In DECnetnetworks, the NMCCjDECnet Monitor system, orNMCC, can provide this information at one centralpoint.Figure 1MANAGER"THINK"MONITOR "LOOK" "ACT" CONTROLNETWORKMonitor Control Feedback LoopRequirements fo r a Network ManagerA network monitor like the NMCC system mustmeet many requirements.: The most imponantones to consider in designing such a product aredescribed as follows: :I• Multiple managers - A network may havemultiple network mam1gers, people who allaccess the monitor simultaneously. The monitormust allow performance data and calculationprograms to be shared among those managers,even though they will typically beasking for different types of information.• Multiple styles of usage - Network managersuse monitors for different purposes; hence,they have different styles of usage. The fivestyles of usage that are encountered are1. Batch, characterized by the automatic productionof periodid reponsI2. Routine, an intedctive style whereinI .monitoring is done · at fixd time periods(e.g., every morning when the user comesto work)3. Browse, an interactive style wherein monitoringis done on a random basis, whentime is available4. Alarm, in which a. monitor notifies theuser of problems W:hen they are detected(A notification could be to color a systemIred on a display, print a console message,signal a beeper, et.)Digital TecbnicaljournalNo. 3 September 1986129