User's Manual
37
3.0 Modem Setup Options
The following two options are available through the V42 SELECTION screen:
The Protocol option is available for Hayes, V.25 bis, Dumb, and Leased-Line
modes (except V.33).
• LAPM/MNP — The Modem attempts to establish a connection using
the V.42 link access protocol (LAPM/MNP). This is the primary error
correction protocol under the CCITT V.42 standard. If such a connection
cannot be established (because the other modem does not support LAPM
or is not configured for LAPM), the Modem attempts to establish a
connection using MNP Class 5 as the fallback error correction protocol.
NOTE
When operating in LAPM mode, the Modem uses V.42 error correction
unless V.42 bis is enabled via the V.42 bis option. (V.42 and V.42 bis
error-correction both use LAPM.)
• LAPM ONLY — The modem only attempts to establish an LAPM
connection (will use only V.42 or V.42 bis error correction).
• MNP ONLY — The modem will only attempt to establish an MNP connection.
NOTE
If a connection cannot be established using the selected protocol (LAPM/
MNP, LAPM ONLY or MNP ONLY), the action the Modem takes depends
on the V.42 mode setting.
V.42 bis Operation is available for Hayes, V.25 bis, Dumb, and Leased-Line
modes (except V.33). V.42 bis operation provides error correction with
data compression. Like V.42 error correction, V.42 bis uses the link access
protocol (LAPM). V.42 bis operation may be enabled or disabled.
The Break Handling option is available for Hayes, V.25 bis (Async only),
Dumb, Leased line modes (except V.33). When error correction is active,
a break signal is relayed with an attention packet. The break-handling
option determines how the attention packet is sent.
• NONE — No attention packet is sent.
• DESTRUCTIVE/EXPEDITED (DESTR/EXP) — All data in the buffer
is deleted; the attention packet is then passed through the channel.
• NON-DESTRUCTIVE/ EXPEDITED (NDT/EXP) —The attention packet
is passed through immediately, but data in the buffer is not deleted.
• NON-DESTRUCTIVE/NON-EXPEDITED (NDT/NEXP) — The
attention packet is passed through the channel in sequence, and any
data is buffered; this preserves the sequence of data and breaks received.