SNMP
SNMP support provides NNM's real power. With SNMP support, NNM can do more than ping addresses on network systems. NNM can monitor, record, and generate events from numeric elements (e.g., interface packet counts, protocol statistics) that the network device maintains in its MIB.
You provide the information that NNM needs to access the MIB data in your SNMP devices. When you configure SNMP in a device, you configure community names (i.e., passwords that permit read-only or read-write access to data that the device maintains in its MIB). Frequently, SNMP devices default to a read-only community name of Public. NNM ships with Public configured as the global default community name in the SNMP configuration panel. If you establish a standard community name, you can configure it as a global default community name in NNM. NNM lets you configure community names by IPX network number, range of IP network numbers, or individual IP or IPX device addresses.
Using the community names you supply to gain access to your SNMP equipment, NNM queries and uses MIB data for network discovery. NNM also uses MIB data to monitor system health, generate events based on threshold values you set, and take other programmed actions you define to occur when the software generates an event.
During my test, I set up an event to monitor the operational status of several Ethernet ports in my switch. NNM generated a normal event log entry. (In this case, I also configured the event to use the NET SEND command to send a message to my user ID with information about the source of the alert.) On the Options menu, I clicked Data Collection & Thresholds: SNMP to configure events.
Defining Expressions
NNM lets you define expressions, which are values calculated from multiple MIB elements and used in the same way you would use individual MIB values as threshold values for event generation and for viewing or collecting data. Expressions improve your system's monitoring and data-collection capabilities. NNM predefines two expressions: Interface % Utilization and Disk % Utilization. Adding expressions isn't easy: You must use a text editor to modify the MIB expression configuration file and restart the NNM services that access that file. (I suspect this area is destined for enhancement in the future.)
Desktop Management
For desktop management, NNM supports two interfaces out of the box: Desktop Management Interface (DMI) and SNMP. NNM includes a remote DMI client for use on HP PC clients that support DMI 2.0 or HP-Remote DMI 1.1 and run Windows 3.x or Windows 95. You can query PCs that support DMI for configuration information that DMI provides, and you can monitor these PCs for DMI-based events.
Enterprise-Class Surveillance
You can deploy NNM as a powerful surveillance tool in your network war games. If you deploy NNM with other modules in the OpenView line, you'll have an enterprise-class systems-management solution.