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New strategies for dial-up modem users.

It is clear, even to the casual observer, that dial modems are by far faster than ever...with the likelihood of getting even faster in the near future.

Is this just anothr fad or fancy of the industry, or is there a real application for such devices?

There is a practical side to this now that switched access has come down in price and dedicated service is no longer a cost-effective alternative. High-speed dial-up access may not fit the needs of every user, yet there are users who could achieve real cost savings with this technology. Consider the case of AAA Inc. (All American Appliance), as Eastern discount appliance chain store operation. There are 67 store locations directly linked to the mini computer system at their New Jersey headquarters. Via point to point dedicated access lines, the cost to link stores averages $625 per line or over $41,000 per month.

Each store generates about 1,575 transactions per week for customer orders, warehouse orders, credits, and inventory checks. Other transactions not included are employee time, cash drawer operations, credit card inquiry, and other administrative transactions. An average weekly store transaction load utilizes 2,363 minutes per week (over 4.8 and 9.6 kb/s lines.)

However, a V.32bis dial-up modem could reduce this to 780 minutes per week or less, depending upon the vendor's bit compression scheme.

For example, a Codex 3260 series V.32bis modem at 38.4 kb/s throughput, might reduce this to 787 minutes per week, while an AT&T 3810 Software Defined (SD) series dial-up modem at 57.6 kb/s, would drop this to under 600 minutes per week.

In this case communications costs of $41,000 per month could be reduced to approximately $5,418 per month (at 13.5 cents per minute).

Clearly, V.32bis modems utilizing V.42bis with MNP 5 provide the user with a viable alternative to dedicated leased-lines.

More flexible strategy

The new dial-up modems offer the network planner the best of two worlds with some modems combining dial-up with conversion to two/four wire leased-line arrangements all in the same box.

This allows the network planner to start out with a dial-up strategy and then later move to a dedicated leased-line arrangement if necessary.

For example, the 3810 SD modem, which was announced at the ICA 91 show in Anaheim this past June, provides a bridge from a high-speed dial-up to a high-speed leased-line strategy.

This modem can be downloaded with firmware that will convert it from a V.32bis dial-up modem to a two/four wire (V.33/V.29) leased-line application.

In the case of AAA Inc.'s application, such flexibility would allow AAA's MIS manager to change specific store locations that warranted reconfiguration from a dial-up to a leased-line arrangement without changing out equipment. In this way, trasmission costs between the stores and the central computer could be tailored to seasonal changes.

Not all migrations are painless. However, most of the V.32bis modems on the market are backward compatible with older modem standards. This includes V.32 at 9.6 kb/s, V.22bis at 2.4 kb/s, AT&T 212A and V.22 at 1.2 kb/s and 1030 at 300 b/s. This would allow the typical small network like the AAA Inc. appliance store network to migrate their modem inventory on a graduated basis.

The new dial-up modem technology comes supported with a full complement of self tests, local and remote loop backs with some products supporting V.54 test standards.

Central site carriers equipped with dial-up modem cards provide for convenient modem pooling and allow centralized network control. A good example of this is the AT&T Compshere 3000 and the Racal-Milgo RDM 1690 chassis units.

Special network management systems, such as AT&T Paradyne's non-disruptive Compshere 6700 Dial Network Management system and Racal-Milgo's CMS 400 are Pc based. These can be purchased separately for MS-DOS, 386/486 platform products and utilize window-based, menu-driven, applications software.

Small networks like the AAA Inc. appliance store chain are fairly common. However, new products like the recently announced V.32bis (AT&T Paradyne 3800 Software Defined (SD), Codex 3260, Racal-Milgo RMD 32222) make it possible for small networks to deploy competitive switched access services such as SDN and VNET to their advantage.

Furthermore, with new forms of Dial Network Management Systems (AT&T Paradyne's nondisruptive 7600 Network Management System, Codex's 9110 Network Manager, Racal's CMS series) the user is now totally independent and capable of pursuing a proactive course in the management of their network.
COPYRIGHT 1991 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991 Gale, Cengage Learning. All rights reserved.

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Title Annotation:Modem Update
Author:Llana, Andy
Publication:Communications News
Date:Sep 1, 1991
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