DTJ Number 3 September 1987 - Digital Technical Journals

The Evolution of Network Management Productssuch trends, for example, an on-line histogram oftraffic or errors over the past week for a specifiedline.Over a long time period (weeks or months) ,the network manager is concerned with planningissues, such as how to configure the network sothat its performance and reliability meet theusers' needs. Information about the current network,its performance and reliability, and theworkload presented to it is invaluable. Thisinformation is all available from the DECnetmonitor via traffic and error reports over specifiedlong-term intervals for specific networkcomponents.Function DistributionA key to the design of the DECnet monitor was tobalance the functions that could be distributedmost advantageously with those that could I?ecentralized. The advantages of centralized informationwere described earlier. However, themonitor's design had to incorporate the flexibilityand other advantages of the existing distributednetwork management features built intothe DECnet software.As discussed earlier, each DECnet system has amanagement agent that maintains data about thatsystem and makes it available to a network managerat a remote location. That composite bodyof data must be collected, analyzed, and stored insome central database, after which it can be distributedto the system managers. The DECnetmonitor gathers this data at user-specified intervalsusing the standard DNA management protocol,NICE, originally used only by NCP. The datacollected concerns counter values, and statusand operational parameters for the lines, circuits,and nodes in the network, including thosefor DECnet, X.25, and SNA connections.The central database supports remote sharedaccess from users. The DECnet monitor provideseach network manager with a separate presentationinterface to the shared data. Data distributionis accomplished via an enhanced managementprotocol, an extension to NICE needed tosupport the additional functions provided by theDECnet monitor.Usage StylesEase of use through human engineering was amajor goal of the DECnet monitor, reflected inthe graphical presentation of information that isdifficult to express in other ways (e .g., the topo-logical map) . Yet the command syntax and presentationof information for the more basic capabilitieshave been derived from those in theoriginal DNA network control program.Network managers have different styles ofusing monitoring. The DECnet monitor supportsthree usage styles: batch, interactive, and alarm.In batch usage, reports are automatically generatedat set intervals. This style, oriented tomedium- and long-term planning needs, is usedmost often to produce summaries of networkmanagement information.Interactive usage is driven by user commands.The DECnet monitor's interactive user interfaceadds many new commands and dynamicallyupdated displays to the static displays availablefrom NCP. These capabilities provide automatedmonitoring capabilities on line. With theseadded functions, it was impossible to keep themonitor's syntax identical to that of NCP's; however,there is a definite family resemblance.Interactive usage is oriented toward short- andmedium-term management needs.In alarm usage, the monitor initiates a signal toindicate a problem to the user (for example,turning red the symbol of a system on a topologymap) . Alarms are oriented toward short-termproblem solving.Design of the DECnet MonitorThe most important decision we made in designingthe DECnet monitor was to limit the productto monitoring; we did not attempt to control thenetwork as well. Network managers reallyneeded more help in monitoring, since NCP'scapabilities in this area were primitive, althoughits control capabilities were perfectly sufficient.Including both monitoring and control was simplytoo much to attempt in a single developmenteffort.With these general requirements in mind, theDECnet monitor was designed to have the followingfive functions:• Collect management data from the networkcomponents• Store the management data in a centrallocation• Distribute data to users• Evaluate the collected data into meaningfulinformation (statistics, configuration description,etc.)124Digital Technical JournalNo. 3 September 1986