3768

Error Correction and Data Compression

Table 21. V.44/V.42/V.42 bis and MNP Data Modem Command Descriptions (Continued)

Command

Default

 

Description

 

 

 

 

 

V.44 Data Compression: This command controls the V.44 data compression function if provided in the

 

 

DCE. It accepts the following sub parameters:

 

 

m=[<direction>[,<compression_negotiation>[,<capability>[,<max_codewords_tx>[,<max_codewords_rx>

 

 

[,<max_string_tx>[,<max_string_rx>[,<max_history_tx>[,<max_history_rx>]]]]]]]]]

 

 

<direction> specifies the desired direction(s) of operation of the data compression function.

 

 

0

Negotiated… no compression

 

 

1

Transmit only

 

 

2

Receive only

 

 

3

Both directions, accept any direction

 

 

<compression_negotiation> specifies whether or not the DCE should continue to operate if the desired

 

 

result is not obtained.

 

 

0

Do not disconnect if Rec. V.44 is not negotiated by the remote DCE as specified in

 

 

 

<direction>. Always set to 0.

 

3, 0, 0,

<capability> specifies the use of stream method, packet method, multi-packet method.

 

0

Stream method

 

471,

 

1

Packet method

 

942,

 

 

 

+DS44=m

140,

2

Multi-packet method

 

140,

<max_codewords_tx> specifies the maximum number of codewords which should be negotiated in the

 

1884,

 

transmit direction.

 

3768

 

256 to 65536

 

 

 

 

 

 

<max_codewords_rx> specifies the maximum number of codewords which should be negotiated in the

 

 

receive direction.

 

 

256 to 65536

 

 

 

<max_string_tx> specifies the maximum string length to be negotiated in the transmit direction.

 

 

32 to 255

 

 

 

<max_string_rx> specifies the maximum string length to be negotiated in the receive direction.

 

 

32 to 255

 

 

 

<max_history_tx> specifies the maximum size of the history buffer to be negotiated in the transmit

 

 

direction.

 

 

 

512

 

 

 

<max_history_rx> specifies the maximum size of the history buffer to be negotiated in the receive

 

 

direction.

 

 

 

512

 

 

 

 

 

 

32-bit Frame Check Sequence: Controls the use of 32-bit frame check sequence option in V.42.

+EFCS=m

0

0

Use 16-bit FCS

1

Use 32-bit FCS if available in remote DCE; otherwise use 16-bit FCS

 

 

 

 

2

Use 32-bit FCS if available in remote DCE; otherwise disconnect

 

 

 

 

NOTE: An asterisk (*) denotes the factory-default setting.

536EX Chipset Developer’s Manual

61

Intel Confidential

Page 61
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Intel manual Intel Confidential, Error Correction and Data Compression, 536EX Chipset Developer’s Manual, 3768, +EFCS=m