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Dial up modem selection process
- From: Russell J Dwarshuis
- Date: Tue Sep 14 11:12:14 1993
Some people had problems reading the attachment on this message, so
I'm resending it without the attachment. Sorry for the inconvenience.
The following may be of use to other Merit members in selecting new dial
up modems for use in central pools. The U of M chose the U.S. Robotics
Total Control WAN Hub system.
-Russell Dwarshuis
Reasons for selection of U.S. Robotics Total Control Wan Hub modems.
The University of Michigan ITD/Network Systems has recently chosen a vendor
for a major expansion of the dial up modem pools. This expansion was
necessary due ton congestion of the existing modem pools, and to implement
a new modem pool for the hardware that is going to replace the SCPs.
It is difficult to gather performance statistics and find defective
modems in large modem pools, and there is a pending standard (called
"V.fast" in the industry) for 28.8kbps modems. We intend to implement
the new high speed modems when the standard is ratified. For these
reasons, we opted not to buy more of the modems that we had been
buying and instead got bids for modems that incorporate a management
system and can be upgraded to the 28.8kbps standard.
The U of M sent out a Request for Quotes to all of the major modem
manufacturers. Responses were received from the following companies:
Motorola Codex
Racal-Datacom
Microcom, Inc.
NEC America
Penril Datacom
U.S. Robotics
Motorola UDS and AT&T Paradyne chose not to respond.
The final selection was made by making a spreadsheet with numeric
grades for how well the modem system met the selection criteria. A
weighted sum gave a final score. The highest score was the winner.
The selection criteria were as follows:
Weighted price. A higher score means a lower price. Modems that were
approximately equal in price were given the same score. The price per
modem was determined by the cost of a vendors rack when it was full of
modems divided by the number of modems per rack. The price was for
conventional modems (no chassis with built in T1 channel banks). The
price score was given a multiplier of 20 for the final score.
Management. This was a subjective score of the usefulness of the
modem management system. It was given a weight of 5 for the final
score.
SNMP. A MIB for the Simple Network Management Protocol is being
developed. In the future, it is anticipated that the U of M will
desire to control and get statistics for the the modems by means of
SNMP. This was a subjective score based on the vendors plans for
implementing SNMP. It was given a multiplier of 4 for the final
score.
High speed. This was a subjective score of the likelihood of the
manufacture implementing either a new modem that would fit into
current chassis or an upgrade kit for existing modems. There have
been articles written in the trade journals questioning the viability
of upgrade kits due to technical issues of the pending V.fast
standard. The score was given a multiplier of 3 for the final score.
Channel Bank. Several vendors responded with prices for modems that
incorporate channel bank equipment. This may be desirable because of
possible future price breaks on delivering large number of phone
circuits on T1 (instead of individual POTS lines.) It could also give
better performance because of the reduction of Transmission
impairments and train-up time inherent with this technology. The
score was given a multiplier of 3 for the final score.
Quality. There have been articles written in the trade journals
comparing different modems. Some modems work on impaired circuits
better than other modems. Also, some modems have more flexible
configuration options than others. The score was based on these
factors, in addition to the construction quality of the modems. The
score was given a multiplier of 4 for the final score.
Availability. Several of the manufacturers bid modem systems that had
just been released, and could therefore be more subject to production
problems. Others have been on the market for a long time and can be
shipped immediately. Since there is an urgent need for more modems, a
score was given for availability. It was given a multiplier of 5 for
the final score.
Warranty. This score was the average of the rack and modem warranty
in years. It was given a multiplier of 1 for the final score.
Additional features. Several of the vendors have systems for which they
plan on offering built in terminal server and/or ISDN capability. We
may need to implement these features in the future, so a rating was
given for this category. It was given a weight of 2.
Price Rating Managem't
Codex 3 3
Racal 2 4
Microcom 4 3
NEC 2 2
Penril 4 3
U.S. Robotics 4 4
weight 20 5
SNMP High speed Channel bank Quality
0 4 0 5
4 5 5 4
0 3 0 3
0 0 0 1
3 5 4 4
4 5 5 3
4 3 3 4
Availability Warranty Additional Features Overall rating
5 1.5 0 134
5 2 3 155
5 1 0 142
3 1 0 70
5 1.5 0 177
3 2 5 185
5 1 2 235
The U.S. Robotics part numbers selected were: 000479-00 (Chassis,
power supplies and controller card), 000497-00 (Dual V.32bis Analog
Modem set), and part number 000427-00 (IPC Console software Rev. 3.2).
There are also quad V.32bis modem cards (which are not upgradeable to
V.fast) for up to 64 modems per chassis. If you'd like to get sales
literature, try contacting Audrey Engleman at 1-800-292-2988.
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