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Changing Technology and Industry Mean New Approaches to Network Management.

Today, a centrally operated network management system is essential to efficient data network control. Without network management, you would need trained technicians at each network site 24 hours a day to analyze, troubleshoot and then repair a problem. A situation like that is difficult to manage even if the cost could be afforded.

Since the beginning of the digital data communications test business in the 1960s, many data line monitors have been introduced. The main thrust has been to give the end user a window into the communications network. This procedure worked well when the protocols and line speeds were simple and slow. In the last few years, this situation has changed. Line speeds are becoming faster and faster. Protocols have changed from easy-to-memorize character patterns to difficult-to-understand bit-oriented multi-level protocols.

As the number of products on the market have expanded, along with the challenges and opportunities created by deregulation, so have the approaches to network management. To look at some of these approaches, we'll use a question-and-answer format, based on commonly asked questions from managers.

What are the advantages and disadvantages of managing a single-purpose, component network versus a multi-purpose integrated systems network?

The advantage of managing a component network composed of modems, telephone circuits, direct digital circuits (DDS) and terminals is that systems and test equipment are available for the management and testing of this type of network. Network management systems provide the telecommunications manager with the tools and reports that are necessary to make intelligent decisions about the network. Network management systems can also provide the user with the ability to reconfigure a network for maximum utilization and uptime.

The obvious disadvantage of a component network is the downtime that can take place if any component within the network should fail. The telecommunications manager must be able to pinpoint the source of a problem quickly and effectively. Once the source of a problem has been identified, the manager must also have the ability to restore the network to full operational status as rapidly as possible.

The advantage of an integrated system network, which can be a local-area network (LAN) or a packet-switching network, is the inherent reliability of these networks. The lower amount of different components in a network equates to fewer failures and lower downtime. The ability of a packet-switch network to re-route data around a failed component automatically is a great advantage to the telecommunications manager.

The disadvantage of an integrated network is the present lack of management systems and test equipment to effectively diagnose problems on this type of network. If a failure should occur, the inability to take effective action upon the failure can cause downtime.

How does the communications manager avoid ad hoc design that invariably results in no clear structure and no resource sharing?

To avoid ad hoc design of a communications network, the communications manager must adhere to the "6 P" principle: "Proper Prior Planning Prevents Poor Performance." Need a Firm Plan

The rapid expansion of data communications within an organization can lead to an unmanageable network with a higher cost associated with it. An overall communications plan can go a long way toward providing systematic growth and expansion of a network. At the same time, it can also provide lower cost for the network.

The communications manager must look toward tomorrow and not just toward today. Network management systems must provide expandable capabilities that match the overall communications plan of the organization. Too often, network management systems are procured that provide only a short-term solution to a problem or need. This system usually will cause a future problem to develop, which in turn will cause further costs.

An overall communications plan is not easy to develop. It will be necessary for departments within an organization to cooperate with the communications manager and, in fact, be an integral part of the plan. Only through cooperation will it be possible for the communications plan to succeed. Success will assure rapid, reliable and cost-effective data communications. Mixing Voice and Data

How does the communications manager provide a cost-effective channel for the intermix of voice and data?

The basic problem of mixing voice and data has been cost. Digitizing voice for transmission has been and continues to be quite expensive. The problem is one of bandwidth required for both data and voice. One method of reducing the overall cost is satellite transmission. If satellite transmission is used for data, the satellite's wide bandwidth can be used for digitized voice, also. Another method would be to use T1 carrier facilities (1.544 Mb/s). In essence, the sharing or mix of voice and data would take place only on a "trunk" circuit between hub locations. This sharing or mixing would be performed by a multiplexer. The actual digitizing of voice would be performed within the PBX or at the telephone handset itself.

The actual mixing of voice and data at any other location in a network other than a trunk circuit is very difficult and costly. The very nature of the new data communications protocols (SNA and X.25) virtually prohibits the mixing of voice and data. There are PBXs that will permit a limited amount of data to pass through them. However, these PBXs are not compatible with the newer protocols, and the speed at which the data circuit can operate through the switch is also limited.

What is diagnostic data?

Diagnostic data is information that tells the communications manager what is happening on the network. It is information that will enable intelligent decisions to be made about the network.

Diagnostic data can take many forms. It can be an alarm indication for loss of carrier on a circuit, an increase in response time on a specific line or terminal, or a report that informs the communications manager that there have been five service calls on one modem within a week. It is the basis for a network management system. Depends On Data Interaction

The minimum amount of diagnostic data that is required is dependent upon the network management system and how it interacts with the data. Typically, the EIA RS-232-C interface, between a modem and terminal device, can provide a large amount of diagnostic information to a network management system. This can be as simple as providing an alarm indication if a control signal should be lost or as complicated as the analysis of data and its protocol. Diagnostic data can also be obtained from measurements of a telephone circuit while it is operational. Off-hour automatic testing can be performed, such as a BERT test, with results tabulated and any problem circuits identified. The network management system should interact with the diagnostic data and provide the communications manager with easy to understand information with the options based upon this data.

The ability to diagnose problems and trends on a network are performed by electronic devices that can monitor the network passively or interactively test certain parameters within a network. The diagnostic device sends the alarm indication or test results to a centrally located management console. There it can be interpreted by the operator and acted upon. Usually, the operator of a network management center will be aware of a problem before the end user realizes something is wrong. In addition to the normal tech-control functions of diagnostic data, the network management system also provides data processing functions for this data. Reports can be generated based upon the diagnostic data that will provide the communication manager with information to effectively "manage" the network--taking actions that will prevent problems from reoccurring. Through response-time measurements and traffic loading statistics, the manager can optimize the network and thereby reduce costs while providing better service to end users. Handling Diagnostic Data

How should diagnostic data be handled: by separate lines, by subchannels?

Diagnostic data can be handled by either separate lines or subchannels. The criteria that will decide which will be used include cost, reliability and speed. Typically, the diagnostic device will determine which method is to be used. For example, a modem diagnostic device that monitors a remote modem for faults (wrap box) will use a subchannel on the main data communications path. A modem wrap box is a communications test/diagnostic instrument used to adapt existing data communications networks to central network control and management. It monitors modem and terminal functions, both digital and analog. It has the capability of performing remotely controlled tests of modem, communication line and terminal functions. This permits individual drops or entire network segments to be evaluated automatically. If separate lines were used to control this type of device, the cost would be very high. At a hub or nodal location where one diagnostic device would monitor and control a number of circuits, a separate circuit would typically be used for both reliability and speed. If the diagnostic channel were to have a problem, it could be backed up by a dial-up circuit.

For those diagnostic devices that are used only for in depth testing, such as a data-line monitor, the diagnostic path would typically be a dial-up circuit. This form of communications is both cost effective and reliable.

Most network management systems will employ several methods of transmission and control for diagnostic data. A combination of methods will ensure reliable, cost-effective diagnostic data in a timely manner.

Network management systems are available in two basic configurations: vendor-dependent and vendor-independent. Vendor-dependent systems require a user to procure certain network components (such as modems and terminals) from the network management system supplier. This may cause a user to be unable to take advantage of new technology and other product advances as the network expands. Vendor-independent network management systems do not require a user to procure network components in order for the network management system to operate. This permits a communications manager to take advantage of new developments in both products and services and thereby provide users with an up-to-date, reliable and cost-effective network.
COPYRIGHT 1984 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1984 Gale, Cengage Learning. All rights reserved.

Article Details
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Author:Markulec, M.
Publication:Communications News
Date:Nov 1, 1984
Words:1652
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