Managing NerveCenter
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Understanding NerveCenter - Main NerveCenter Components -
NerveCenter is a distributed client/server application and includes the following components:
For information about these components, see the following sections:
The NerveCenter Server is responsible for carrying out all of the major tasks that NerveCenter performs. For example, it handles the polling of SNMP agents, creates NerveCenter objects such as the finite alarms mentioned earlier, and makes sure that state transitions occur at the appropriate times. The server also performs all actions associated with state transitions.
The server can run as a daemon on UNIX systems and as a service on Windows systems. This capability to run in the background has important implications with regard to using NerveCenter at remote sites. You can install the server and database at a remote office and have that server manage the local network, yet control the server (via the NerveCenter Client) from a central location. Servers located at remote sites can forward noteworthy information to a server at the central location as required.
The NerveCenter database is primarily a repository for the NerveCenter objects that make up a set of behavior models. The principal objects used in these models are:
For brief explanations of what these objects are and how they are used, see Objects in the Database.
A set of objects that define many useful behavior models ships with NerveCenter and is available as soon as you've installed the product. For a list of these predefined behavior models, see the section Predefined Behavior Models.
On UNIX systems, the NerveCenter database is implemented as a flat file. On Windows systems, the database can be either a Microsoft Access database or a Microsoft SQL Server database.
This section contains brief definitions of the basic objects used in the construction of behavior models.
A node represents either a workstation or a network device, such as a router. Each node has an attribute called its property group that controls which behavior models NerveCenter will employ in managing the node.
As mentioned above, each node has a property group. This property group is simply a container for a set of properties, which are strings that typically either describe the type of node or name an object in the MIB used to manage the node. It is actually a node's properties, rather than its property group, that determine whether a particular behavior model will be used to manage that node.
A poll defines what MIB variables NerveCenter should request the values of, how those values should be evaluated, and what action the poll should take. If the poll takes an action, it will be to fire a trigger, which may cause a state transition in one of NerveCenter's finite state machines.
A trap mask describes an SNMP trap and contains the name of a trigger. If NerveCenter receives an SNMP trap that matches the description given in the trap mask, NerveCenter fires a trigger with the name defined in the trap mask. If NerveCenter receives a trap that does not match a trap mask, it discards that trap.
NerveCenter's finite state machines are called alarms. Each alarm defines a set of operational states (such as Normal and Down) and transitions between the states. Transitions are effected by the receipt of the proper trigger and can have actions associated with them. If actions are associated with a transition, the server performs these actions each time the transition takes place.
Once a set of managed nodes has been defined, NerveCenter's monitoring activities are controlled by a set of behavior models. A behavior model is the group of NerveCenter objects required to detect and take action upon a single network condition, such as high traffic on an interface.
The central object in each behavior model is a deterministic finite state machine called an alarm. For instance, the alarm shown in Alarm State Diagram tracks the level of traffic on an interface.
The possible states in this alarm are low, medium, and high. And these states have the severities Normal, Medium, and High, respectively. (The color of each state denotes its severity.) The gray rectangles in the alarm represent state transitions.
What about the inputs and outputs of the state machine? The inputs are called triggers and can come from several sources. For example, one predefined NerveCenter poll queries the SNMP agent on a device for the level of traffic on, and the capacity of, each interface on the device. If the level of use exceeds a certain percentage of the capacity for an interface, the poll fires the trigger mediumLoad, which can cause a state transition in an alarm.
The outputs of an alarm are called alarm actions. These actions are associated with the transition from one state to another by the designer of a behavior model, and NerveCenter performs these actions each time the transition occurs. There are many possible actions, including the following:
When you install NerveCenter and create a new database, that database contains the objects that make up a number of predefined behavior models. These include behavior models for:
NerveCenter also includes predefined behavior models that you can import to monitor specific vendors' devices and additional models for troubleshooting, interface status, data collection, and downstream alarm suppression. For more information about behavior models, see Designing and Managing Behavior Models.
| Detecting Conditions | The NerveCenter User Interface |
| 29 July 2003 |