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MNP (MICROCOM NETWORKING PROTOCOL)
Provides error control and data compression when your modem is
communicating with another modem that supports MNP. (MNP classes 1
through 4 are specified by CCITT V.42 as a backup error control scheme
for LAPM.) Your modem supports five MNP classes. Each MNP class has all
the features of the previous class plus its own.
* MNP class 1 (also called block mode): Sends data in one direction
at a time. About 70 percent as fast as data transmissions using no
error correction.
* MNP class 2 (also called stream mode): Sends data in both
directions at the same time. About 84 percent as fast as data
transmissions using no error correction.
* MNP class 3: Sending modem strips start and stop bits from data
block before sending it. Receiving modem adds start and stop bits
before passing the data to the receiving computer. About 8 percent
faster than data transmissions using no error correction.
* MNP class 4: Monitors the quality of the connection and
streamlines the information in the headers of data blocks. If the
telephone line is relatively noise-free, the modem sends larger
blocks of data to increase throughput. If the telephone line is
noisy, the modem sends smaller blocks of data so that less data
will have to be resent. This means more successful transmissions on
the first try. About 20 percent faster than data transmissions
using no error correction.
* MNP class 5: Provides data compression. Sending modem detects
redundant data and recodes it to fewer bits to increase the
effective throughput. Receiving modem decompresses the data before
passing it to the receiving computer. Up to 100 percent faster than
data transmissions using no data compression or error correction,
depending on the kind of data transmitted. (Files that are already
compressed will seem to contain less redundant data and may
therefore take longer to transmit using MNP class 5 than they would
if you were using no data compression.) |