Link Access Procedure for Modems: Difference between revisions

Revision as of 09:47, 23 June 2023

Revision as of 05:44, 26 November 2023

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The larger the [[Payload (computing)|payload]] included in each frame, the smaller the relative cost of transmitting the header and trailer bits. Usually LAPM adds only about 5 percent framing overhead. This is a noticeable improvement over the fixed 25% overhead of start and stop bits required by direct [[asynchronous serial communication]], but obviously such large frames impose a cost in the form of [[Latency (engineering)|communication latency]].

LAPM has an optional Selective''selective reject'' (''SREJ'') functionality which allows it to resend only the corrupted frames, providing faster recovery from an error.

The ITU-T V.42 LAPM procedure is considered more robust than the [[Microcom Networking Protocol]]s (MNP) that preceded it, and has a more sophisticated and powerful data compression option in V.42bis, allowing much greater data throughput.