Page 320 - Optical Communications Essentials

Network Management

310 Chapter Eighteen

origin of faults, the management system might use fault isolation techniques
such as alarm correlation from different parts of the network and diagnostic
testing.
■ Once the faults are isolated, the system issues trouble tickets that indicate
what the problem is and possible means of how to resolve the fault. These
tickets go to either a technician for manual intervention or an automatic fault
correction mechanism. When the fault or degradation is corrected, this fact
and the resolution method are indicated on the trouble ticket, which then is
stored in a database.
■ Once the problem has been fixed, the repair is operationally tested on all
major subsystems of the network. Operational testing involves requesting per-
formance tests, tracking the progress of these tests, and recording the results.
The classes of tests that might be performed include echo tests and connec-
tivity examinations.

An important factor in troubleshooting faults is to have a comprehensive
physical and logical map of the network. Ideally this map should be part of a
software-based management system that can show the network connectivity
and the operational status of the constituent elements of the network on a dis-
play screen. With such a map, failed or degraded devices can be viewed easily,
and corrective action can be taken immediately.

18.2.5. Security management
The ability of users to gain worldwide access to information resources easily and
rapidly has made network security a major concern among network adminis-
trators. In addition, the need of remote users and personnel who telecommute
to access corporate data from outside the corporation presents another dimen-
sion to network security. Figure 18.3 shows some of the points in a network and
at its external interfaces where security may be an issue. Network security covers
a number of disciplines, including

■ Development of security policies and principles
■ Creating a security architecture for the network
■ Implementing special firewall software to prevent unauthorized access of cor-
porate information from the Internet
■ Applying encryption techniques to certain types of traffic
■ Setting up virus protection software
■ Establishing access authentication procedures
■ Enforcing network security

The principal goal of network security management is to establish and enforce
guidelines to control access to network resources. This control is needed to

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