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]