Filter
Top Products
AT Commands
Page 29
Error Correction
Error Correction Protocols
This section examines the error correction and data compression features of your modem. The
modem offers both V.42 (LAP-M) and MNP® (Microcom Networking Protocol™) error
correction protocols. These protocols allow data errors to be detected by the receiving modem,
provide flow control between remote systems and improve the overall throughput of data
transfers.
Your modem also supports V.42bis and MNP5 data compression. V.42bis is a high performance
data compression enabling you to speed up, theoretically by four times, data throughput on
some types of data. MNP5 allows you to speed up data throughput by up to two times on
some types of data.
☞☞
☞☞
☞
Aust Modems: Before dialling into an AUSTPAC V.22 or V.22bis
service, error correction must be disabled using the \N0 command.
Two types of error correction protocols are offered by your modem; V.42 (or LAP-M) and
MNP.
☞☞
☞☞
☞
Error correction protocols are not available when a V.23 connection is
established.
V.42 is an international standard for error correction between modems. V.42 ensures any errors
introduced into your data by telephone line noise is automatically corrected before it is received
by your computer. Because V.42 is a ITU standard, it has become very popular in modems all
over the world.
V.42 also supports a fallback mode to MNP, in order to remain compatible with modems
introduced prior to V.42.
Before V.42 existed, MNP was the de-facto standard for modem error correction. MNP classes
2-4 are supported by your modem for error-correction (an additional class of MNP is supported
for data compression). Because MNP is a far less complex error correction protocol than V.42, it
out-performs V.42.
The section titled “Which Error Correction Do I Use?” provides more information about the
performance and compatibility merits of V.42 and MNP.
The \N command is used to select the type of error correction used by your modem.