RFC 916 (rfc916) - Page 4 of 54

Reliable Asynchronous Transfer Protocol (RATP)

RFC 916                                                     October 1984
Reliable Asynchronous Transfer Protocol


2. Packet Specification

   RATP transmits data over a full-duplex communication link.  Data may
   be transmitted in both directions over the link.  A stream of data is
   communicated by being broken up into 8-bit pieces called octets.
   These octets are serially accumulated to form a packet.  The packet
   is the unit of data communicated over the link.  The protocol
   virtually guarantees that the data transmitted at one end, if
   received, arrives unaltered and intact at the other end.

   Within an octet all eight bits contain data.  All eight bits must be
   preserved by the link interface and associated device driver.  In
   many operating systems this is ensured by placing the connection into
   RAW or BINARY data mode.  During normal operation packets are
   transmitted and acknowledged one at a time over the link in each
   direction.  Each packet is composed of a HEADER followed by a DATA
   portion.  The DATA portion may be empty.

      NOTE: There are some older operating systems and devices which do
      not permit 8-bit communication over an RS-232 link.  Most of these
      allow restricted 7-bit communication.  RATP can automatically
      detect this situation during connection initiation and utilizes a
      special packing strategy when full 8-bit communication is not
      possible.  This is entirely transparent to any client software.
      See Appendix I for a discussion of this case.
























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