Technical Reference for ZyXEL omni.net series
9-2
Standard
Speed (bps)
Notes
V.21 300
V.22 1200
V.22 bis
2400 or 1200
V.32
9600 or 4800
V.32 bis
14400, 12000, 7200
V.34
33600 – 2400
V.90
56000 – 28000
Table 55. Modem Standards and Speeds
MNP Protocols
MNP (Microcom Network Protocol) is a set of protocols first introduced by Microcom, Inc., and
alter used by many modem manufacturers. It consists of many classes. Class 1 to 4 are for error
correction, and class 5 is for data compression. MNP Class 1 and 2 are obsolete. Normally Class 4
is used for error correction and it uses Class 3 internally.
MNP Class 5 is data compression protocol with a maximum efficiency of 2 to 1. MNP-5 is used
with MNP-4 for error correction.
Xmodem, Ymodem, and Zmodem
These are file transfer protocols. They do error checking and ensure data integrity of the file
transferred. Some variations of these protocols also appear, like Xmodem-1k, Ymodem-G, etc.
The “G” types of protocols do not include error checking. They allow very high throughput rates,
but can be safely used only when the modems use MNP4 or V.42 error protocols and there is no
speed overrun on the computer’s serial port.
Whenever possible, we recommend the use of Zmodem for added security and high flexibility.
Consult your communications program manual for more information on transfer protocols.
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