RFC 801 (rfc801) - Page 2 of 21

NCP/TCP transition plan

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RFC 801                                                    November 1981
                                                 NCP/TCP Transition Plan


   can move into an environment with significantly broader communication
   services.

Discussion
----------

   The implementation of IP/TCP on several hosts has already been
   completed, and the use of some services is underway.  It is urgent
   that the implementation of of IP/TCP be begun on all other ARPANET
   hosts as soon as possible and no later than 1 January 1982 in any
   case.  Any new host connected to the ARPANET should only implement
   IP/TCP and TCP-based services.  Several important implementation
   issues are discussed in the last section of this memo.

   Because all hosts can not be converted to TCP simultaneously, and
   some will implement only IP/TCP, it will be necessary to provide
   temporarily for communication between NCP-only hosts and TCP-only
   hosts.  To do this certain hosts which implement both NCP and IP/TCP
   will be designated as relay hosts.  These relay hosts will support
   Telnet, FTP, and Mail services on both NCP and TCP.  These relay
   services will be provided  beginning in November 1981, and will be
   fully in place in January 1982.

   Initially there will be many NCP-only hosts and a few TCP-only hosts,
   and the load on the relay hosts will be relatively light.  As time
   goes by, and the conversion progresses, there will be more TCP
   capable hosts, and fewer NCP-only hosts, plus new TCP-only hosts.
   But, presumably most hosts that are now NCP-only will implement
   IP/TCP in addition to their NCP and become "dual protocol" hosts.
   So, while the load on the relay hosts will rise, it will not be a
   substantial portion of the total traffic.

   The next section expands on this plan, and the following section
   gives some milestones in the transition process.  The last section
   lists the key documents describing the new protocols and services.
   Appendices present scenarios for use of the relay services.

The General Plan
----------------

   The goal is to make a complete switch over from the NCP to IP/TCP by
   1 January 1983.

      It is the task of each host organization to implement IP/TCP for
      its own hosts.  This implementation task must begin by
      1 January 1982.





Postel
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