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MNP and V.42

Operation modes

The protocol of both modems must be the same. Therefore, if the remote modem supports only class 3 or below, the protocol for the remote modem will be used. If the remote modem does not use MNP, the communication will be made at the speed of the remote modem.

V.42 error correction

The V.42 (ITU-T-Rec V.42) protocol is recommended by the ITU (International Telecommunications Union). V.42 specifies two kinds of protocols, LAP-M (Link Access Procedure for Modem) and MNP classes 2, 3, and 4. This protocol first tries to establish a link to the remote modem with LAP-M. If it is unsuccessful, it tries to connect with MNP. Although this modem uses class 4 correction, it can connect in class 5 to remote modems that support class 5.

Operation modes

The operation mode depends on whether an error-correction protocol is being used.

Normal mode

Errors are not corrected, even if communication speed is different between a personal computer and modem, or between modems, the buffers in the modem and the flow control function permit communication without changing communication speed.

Reliable mode

This mode is used with MNP or V.42 protocols to ensure error-free communication.