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Network Working Group J. Postel Request for Comments: 128 UCLA Category: C.2, D. Computer Science NIC #5844 21 April 71 Obsoletes: none Updates: none

 It is somewhat unclear what to do with the Byte size parameter now
 allowed by the 2nd level protocol.  I can conceive of an
 implementation in which the 3rd level programs never see this
 parameter.  Crocker implies in RFC 123 that control of this parameter
 is given to the 3rd level programs and that both sender and receiver
 may specify values of the byte size to the NCP.
 There are at least two interpretations if the sender and receiver
 specify different byte sizes.
 I.  The first is that the connection is illegal.
 II.  The second is that the NCP must parse the data stream on receipt
     from the network and into a buffer according to be byte size of
     the sender, and subsequently parse the data stream on transfer
     from the buffer to the receiver.  In this second case there are
     two sub cases.
     A. One is to consider bits as the basic unit.
        For example, if the sender specified byte size = 5 and the
        receiver specified byte size = 3 then
        Receiver                   NCP                    Sender
        -+---+---+---+---+      +--------+      +-----+-----+---
         |000|001|010|011| <--- | Buffer | <--- |00000|10100|11
        -+---+---+---+---+      +--------+      +-----+-----+---
     B. The other is to consider bytes as the significant unit and pad
        (on the right or left?) or truncate to make things fit, or
        other transformation.
 At UCLA-Computer Science we are contemplating allowing sender and
 receiver to specify different byte sizes and consider bits as the
 basic unit (Case II.A.).  This does not rule out our considering the
 second subcase (Case II.B.).  We may allow 3rd level programs to
 specify a library or user supplied routine to perform the

Postel [Page 1] RFC 128 Bytes April 1971

 transformation between sender and receiver bytes.  Perhaps these
 transformation routines would be written in the Data Reconfiguration
       [ This RFC was put into machine readable form for entry ]
          [ into the online RFC archives by Duncan de Waal 03/98 ]

Postel [Page 2]

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