Network Management

Network Management

network management as monitoring, testing, configuring, and troubleshooting network components to meet a set of requirements defined by an organization. These requirements include the smooth, efficient operation of the network that provides the predefined quality of service for users. To accomplish this task, a network management system uses hardware, software, and humans.
The International Organization for Standardization (ISO) defines five areas of network management: configuration management, fault management, performance management, security management, and accounting managemen




1. configuration management
The configuration management system must know, at any time, the status of each entity and its relation to other entities. Configuration management can be divided into two subsystems: reconfiguration and documentation.
1.1. Reconfiguration
Reconfiguration can be a daily occurrence in a large network. There are three types of reconfiguration: hardware reconfiguration, software reconfiguration, and user-account reconfiguration.
1.2. Documentation
The original network configuration and each subsequent change must be recorded meticulously. This means that there must be documentation for hardware, software, and user accounts.
2. Fault Management
Fault management is the area of network management that handles this issue. An effective fault management system has two subsystems: reactive fault management and proactive fault management.

2.1. Reactive Fault Management
A reactive fault management system is responsible for detecting, isolating, correcting,
and recording faults. It handles short-term solutions to faults.
2.2. Proactive Fault Management
Proactive fault management tries to prevent faults from occurring. Although this is not always possible, some types of failures can be predicted and prevented. For example, if a manufacturer specifies a lifetime for a component or a part of a component, it is a good strategy to replace it before that time.


3. Performance Management
Performance management, which is closely related to fault management, tries to monitor and control the network to ensure that it is running as efficiently as possible. Performance management tries to quantify performance using some measurable quantity, such as capacity, traffic, throughput, or response time. Some protocols, such as SNMP, can be used in performance management.


3.1. Capacity
Every network has a limited capacity and the performance management system must ensure that it is not used above this capacity. For example, if a LAN is designed for 100 stations at an average data rate of 2Mbps, it will not operate properly if 200 stations are connected to the network. The data rate will decrease and blocking may occur.
3.2. Traffic
Traffic can be measured in two ways: internally and externally. Internal traffic is measured by the number of packets (or bytes) travelling inside the network. External traffic is measured by the exchange of packets (or bytes) outside the network. During peak hours, when the system is heavily used, blocking may occur if there is excessive traffic.
3.3. Throughput
We can measure the throughput of an individual device (such as a router) or a part of the network. Performance management monitors the throughput to make sure that it is not reduced to unacceptable levels.
3.4. Response Time
Response time is normally measured from the time a user requests a service to the time the service is granted. Other factors such as capacity and traffic can affect the response time. Performance management monitors the average response time and the peak-hour response time. Any increase in response time is a very serious condition as it is an indication
that the network is working above its capacity.

4. Security Management
Security management is responsible for controlling access to the network based on predefined policy.
5. Accounting Management
Accounting management is the controlling of users’ access to network resources through charges. Under accounting management, individual users, departments, divisions, or even projects are charged for the services they receive from the network.


SNMP (Simple Network Management Protocol

Several network management standards have been devised during the last few decades. The most important one is Simple Network Management Protocol (SNMP), used by the Internet. It uses the TCP/IP protocol suite. It provides a set of fundamental operations for monitoring and maintaining an internet. SNMP uses the concept of manager and agent. That is, a manager, usually a host, controls and monitors a set of agents, usually routers or servers (see Figure).
SNMP is an application-level protocol in which a few manager stations control a set of agents. The protocol is designed at the application level so that it can monitor devices made by different manufacturers and installed on different physical networks.