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communications protocol
asynchronous
Bell 103
Bell 212A
bps
CCITT
communications
full duplex
half duplex
HDLC
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protocol

All communications between devices require that the devices agree on the format of the data. The set of rules defining a format is called a protocol. At the very least, a communications protocol must define the following:
  • rate of transmission (in baud or bps)
  • whether data is to be transmitted in half-duplex or full-duplex mode
  • In addition, protocols can include sophisticated techniques for detecting and recovering from transmission errors and for encoding and decoding data.

    The table lists the most commonly used protocols for communications via modems. These protocols are almost always implemented in the hardware; that is, they are built into modems.

    In addition to the standard protocols listed in the table, there are a number of protocols that complement these standards by adding additional functions such as file transfer capability, error detection and recovery, and data compression. The best-known are Xmodem, Kermit, MNP, and CCITT V.42 . These protocols can be implemented either in hardware or software.

    Communications Protocols



    Protocol
    Maximum Transmission Rate

    Duplex Mode
    Bell 103 300 bps
    Full
    CCITT V.21 300 bps
    Full
    Bell 212A 1,200 bps
    Full
    ITU V.22 1,200 bps
    Half
    ITU V.22bis 2,400 bps
    Full
    ITU V.29 9,600 bps
    Half
    ITU V.32 9,600 bps
    Full
    ITU V.32bis 14,400 bps
    Full
    ITU V.34 36,600 bps
    Full
    ITU V.90 56,000 bps
    Full


    More Information

      Macintosh based networking products
    Home page of Team ASA. Contains information on their high speed network adapters and multi-topology communications protocol products. Updated on May 22, 1998

      NewStar Collaborative Technologies home page
    NewStar is a technology company specializing in voice, data and image compression algorithms specifically designed for communications. Their home page offers links to product and company information, compression technology, and a demo download link. Updated on Jul 3, 1998

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