56K Modem Support; General Notes On 56K Modem Support - Bay Networks 5399 Release Note

56K Modem Support

Release 5.3 introduces support on the 5399 RAC and the 8000 RAC for
56K modems using the Rockwell Semiconductor/Lucent Technologies
K56flex protocol. Support for 56K modems using the U.S. Robotics x2
protocol (also on the 5399 RAC and the 8000 RAC) was introduced in
Release 5.2.
A RAC can be configured for a single 56K protocol only; it may
handle either K56flex calls or x2 calls, but not both.

General Notes on 56K Modem Support

56K modems will not work everywhere. While operating under diverse
conditions, you should expect that in K56flex mode or x2 mode the system
will exhibit negotiation failures, dropped calls, retrains, and
renegotiations at a rate greater than that normally experienced with V.34
connections. In addition, the ability to establish a 56K connection is
extremely dependent on specific line conditions. Therefore, it is normal
for some users to be unable to make a 56K connection every time, or at
all. In such cases, normal V.34 calls will take place.
56K modems do not offer similar performance in both directions, and
both 56K protocols rely on the client modem to determine the final
connect speed. They can achieve 56K throughput only when you are
downloading files. Preliminary test results have shown download speeds
ranging from 33.6 Kb/s to 52 Kb/s. The average download speed is in the
range of 42 Kb/s to 46 Kb/s, as many industry publications have
demonstrated with their benchmark testing. Your results may vary with
the quality of your local phone line and the degree of multiplexing
required to service your neighborhood's voice needs from your local
phone company's central office. 56K modems upload at maximum speeds
of 28.8 Kb/s or 33.6 Kb/s.
Remote Access Software Version 5.3 Release Notes
300115-B Rev. A
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