Configure Branch
8-333980-A2-GB30-40 October 1998
V.42/MNP/Buffer
V.42/MNP/Buffer configuration options determine the
type of error correction and flow control used by the
modems and attached DTEs.
Some choices within this group may not appear
depending upon how previous configuration options have
been selected. If the Async/Sync Mode configuration
option is set for synchronous operation (see DTE Interface
configuration options group), then the V.42/MNP/Buffer
group does not appear on the LCD. Any changes made to
configuration options within this group only take effect
after a disconnect.
Table 8-6 shows each V.42/MNP/Buffer configuration
option as it appears on the LCD, with the Async Dial
factory default setting (the default value if the modem is
just being installed) shown following the colon (:) on the
first line and with all available selections listed on the
second line. Following this is a description of the
configuration option, a description of the available
selections, and any equivalent AT commands.
Table 8-6
(1 of 8)
V.42/MNP/Buffer Configuration Options
*Err Contrl Mode: V42/MNPorBfr
Nxt V42/MNPorBfr V42/MNPorDsc MNP_or_Buffr MNP_or_Disc BufferMode DirectMode
LAPM_or_Disc LAPM_or_Bufr
Determines the type of error control used by the modem. In most cases, V42/MNPorBfr is the best choice. If V.42bis and
MNP are enabled, then the modem uses the following priority for error control negotiation: V.42, MNP 5 and below, and
Buffer Mode. Online changes do not take effect until a disconnect occurs.
V.42/MNP or Buffer – Modem attempts to connect in V.42 Error Control mode. If this fails, the modem attempts to
connect in MNP mode. If this fails, the modem connects in Buffer mode and continues operation. This is also known as
V42/MNP Autoreliable Mode.
V.42/MNP or Disconnect – Modem attempts to connect in V.42 Error Control mode. If this fails, the modem attempts to
connect in MNP mode. If this fails, the modem disconnects. This is also known as Reliable mode.
MNP or Buffer – Modem attempts to connect in MNP mode. If this fails, the modem connects in Buffer mode. This is
also known as MNP Autoreliable Mode.
MNP or Disconnect – Modem attempts to connect in MNP mode. If this fails, the modem disconnects. This is also
known as Reliable mode.
Buffer Mode – Modem does not use error control and allows the DTE rate to differ from the communications line rate.
This mode should only be used if the DTE provides its own error control or if errors in data can be tolerated. This setting
is also known as Normal mode and is valid even if the remote modem is set for Direct mode.
Direct Mode – Modem connects at a data rate equal to or less than the initial DTE interface rate. (The modem never
connects at a data rate greater than the initial DTE rate.) If the modem connects at a data rate lower than the DTE rate,
the DTE must then adjust its data rate to equal the modem rate. Ultimately, the modem speed and DTE speed must be
the same. Direct mode does not support error control or data buffering. Not all DTE and VF rates are available.
LAPM or Disconnect – Modem attempts to connect in V.42 Link Access Procedure for Modems (LAPM) error control
mode. If this fails, the modem disconnects. This setting should be used for cellular connections (at both the mobile and
PSTN sides) when it is known that both sides support V.42.
LAPM or Buffer – Modem attempts to connect in V.42 LAPM error control mode. If this fails, the modem connects in
Buffer mode and continues operation.
NOTE: The modem must be reconfigured for Direct mode before changing the leased-line modulation if V.42 error
control or Buffer mode are enabled with V.32bis on leased lines.
For Async Dial and UNIX Dial, V42/MNPorBfr is the factory default.
For Sync Dial and Sync Leased, DirectMode is the factory default.
AT command equivalent is \N
n
.
*This configuration option is only available if Async/Sync Mode is configured for Async. Refer to the DTE Interface
configuration options group for more on Async/Sync Mode.