RESPONSE TO NWG/RFC 346

John Davidson

June 9, 1972

        Generally, the solutions come from extensions to the original
   design concepts of the BCC 500 distributed communication system.  The
   500 was designed to serve a large number of geographically-scattered
   users each of whom accessed the central computing facility through one
   of several remote concentrators.  [The concept is not too unlike that
   of users at different TIPs all accessing a single host.] Since it was
   felt that in full-duplex, character-by-character interaction, echo
   delays of any noticeable length should not be tolerated, a facility
   was provide whereby the concentrator could provide local (to the
   terminal) echoing when deemed appropriate.  (A character input/output
   microprocessor, the CHIO, in implicit conjunction with the terminal
   user's process executing in the CPU dictated when it was appropriate.)
   The problems associated with coordinating the concentrator and CHIO in
   the partioning of echoing were solved for the BCC 500, but are not
   immediately extensible to the asynchronous message transmissions of
   the ARPANET - especially with the introduction of satellite delays.
   As stated, we are working on some viable alternatives.
   
        It is not known, at present, what effects the incorporation of
   these partitioned echoing techniques might have on the existing net.
   Perhaps local echoing will become a function of User TELNETs; most
   certainly local echoing should be available in the TIP.  But could it
   be incorporated into the IMP so that TIP and User TELNETs can be used
   without change?  If so, what happens to the concentrator's local
   echoing capability in a system such as the BCC 500?
   
        These questions do not have immediate answers.  Other problems
   obviously exist because of the differences in serving system
   conventions for terminal control.  We, in conjunction with the ILLIAC
   group at NASA-AMES, are seeking solutions to such problems in general,
   with an eye toward their implementation

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