P3 Introduction

P3 is is the protocol used to transmit data between client and host software with the America Online, Playnet, and Quantum Link clients. According to former America Online employee Tony Showoff, P3 is an acronym for "Playnet Proprietary Protocol". (1)

1. The company name was not Playnow, no matter what Tony says 😉

P3 contains a number of features, some designed for communication over dialup modems (i.e. unreliable networks). These features include:

• Error detection via CRC
• Flow control using a sliding window
• Reflected packet detection
• Reduced packet transmission by piggybacking