13 HANDSHAKING, ERROR CONTROL,DATA COMPRESSION , ANDTHROUGHPUTThis chapter contains information about: Handshaking Selective Reject V.90 Capabilities Error Control Data compression Getting maximum throughputHandshaking With each call, Courier V.Everything modems go through a linknegotiation process with the remote device. Another name for thenegotiation process is "handshaking.Courier V.Everything modems default to V.90 modulation and try for thehighest possible speed when they attempt to connect with anothermodem: 56 Kbps. If the remote device is not V.34-capable, a connectionis made using the highest compatible modulation scheme (x2,V.34, V.FC,V.32 terbo, V.32 bis, and so on, down to as low as Bell 103, or 300 bps).Selective Reject The Courier V.Everything modem supports Selective Reject for analoguecalls. Selective Reject improves performance on noisy lines by reducingthe amount of overhead incurred when the protocol must resend datadue to errorsWhen Selective Reject is active, only the frame that contained the error isresent, instead of the frame plus all of the following unacknowledgeframes.
