Network Working Group                                        A. McKenzie
Request for Comments #93                                             BBN
Updates RFC's 66, 80                                        January 1971

                      Initial Connection Protocol

        A review of the Initial Connection Protocol (ICP) first
described in RFC 66 and restated in RFC 80 has revealed an area of
ambiguity, which in turn reflects an ambiguity in the Host-Host
Protocol Document No. 1.  This is the definition of the message sent
over the connection from "Server socket #1".  In both referenced
RFC's, the message is defined as "exactly an even 32 bit number".  It
is not clear, however, whether this 32 bit number is meant to follow
an eight-bit "message data type" code or not, stemming from the fact
that the Host-Host Protocol makes provision for such codes but does
not seem to absolutely demand them.

        Only one implementation of an ICP has been documented in the
NWG literature - that at UCSB (RFC 74).  The implementers of this ICP
have apparently interpreted the Host-Host Protocol as demanding a
message data type code, and therefore do transmit a code of zero.

        Steve Crocker indicates (private communication) that the Host-
Host Protocol was intended to require a message data type code.  We
therefore recommend that RFC numbers 66 and 80 be amended to show that
the "even 32 bit number" is preceded by a message data type code of
zero (zero is the only code currently defined).

       [ This RFC was put into machine readable form for entry ]
        [ into the online RFC archives by James Thompson 4/97 ]

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