Black Box MD885A-R3, MD885AE-R2, MD885C-R2, 34336 user manual Modem Setup Options

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.

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