 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 communication latency.LAPM has an optional 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 Protocols (MNP) that preceded it, and has a more sophisticated and powerful data compression option in V.42bis, allowing much greater data throughput.