Network Management Systems (NMS)
Network Management System is defined as the collection of tools that assist human network managers in planning, configuring, controlling and monitoring the computer networks. It covers all the activities and safety measures needed to ensure the effective and efficient use of the resources to be managed. Thus, a Network Management System has to address different functional areas of a computer network and has to fulfill the requirements of the users in these areas. The International Standards Organization (ISO) has defined and categorized functional areas “Management Functional Areas” of a network management system as follows. 1. Fault Management
2. Performance Management
3. Configuration Management
4. Accounting Management
5. Security Management
“The goal of fault management is to detect, log, notify users of, and (to the extent possible) automatically fix network problems to keep the network running effectively.” Fault management involves:
• Determine exact fault location.
• Isolate the faulty area from the other working side. • Repair or replace the faulty device.
• Fault logging.
ISO defined the Performance Management as.
“The goal of performance management is to measure and make available various aspects of network performance so that inter-network performance can be maintained at an acceptable level.” Examples of performance variables that might be provided include network throughput, user response times, and line utilization. SNMP Overview
The Simple Network Management Protocol (SNMP) is an application layer protocol that facilitates the exchange of management information between network devices. It is part of the Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite. SNMP enables network administrators to manage network performance, find and solve network problems, and plan for network growth. This chapter briefly discusses the basic components of SNMP. It also talks about SNMP messages. Management Information Base a logical database that store SNMP parameters is also discussed in this chapter.
An SNMP-managed network consists of three key components:
• Managed devices
• Network Management Systems.
1 Managed Devices
A managed device is a network node that contains an SNMP agent that resides on a managed network. Managed devices collect and store management information and make this information available to Network Management Systems using SNMP . Managed devices, sometimes called network elements, can be routers and access servers, switches and bridges, hubs, computer hosts, or printers.
2 SNMP agent
SNMP agent is a network-management software module that resides in a managed device. An agent has access to a local management information base (MIB). It gets the management information from the MIB and then translates that information to an SNMP compliant language.
3 Network Management System
A Network Management System executes applications that monitor and control managed devices. A Network Management System provides the bulk of the processing and memory resources required for network management. One or more Network Management Systems must exist on any managed network.
Figure 3.1 An SNMP-Managed Network Consists of Managed Devices, Agents, and NMSs 
3.2 SNMP Basic Commands
Managed devices are monitored and controlled using three basic SNMP operations: • Get
1 Get Operation
The get operation is used by a Network Management System to monitor managed devices. The Network Management System examines different network parameters that are maintained by managed devices. The Getnext operation is a variant of the get operation. It is used by the Network Management System to determine the network parameters a managed device supports and to sequentially gather...
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