NCP/TCP transition plan
RFC - Unknown
(November 1981; No errata)
||RFC Editor Note
RFC 801 (Unknown)
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Network Working Group J. Postel
Request for Comments: 801 ISI
NCP/TCP TRANSITION PLAN
ARPA sponsored research on computer networks led to the development
of the ARPANET. The installation of the ARPANET began in September
1969, and regular operational use was underway by 1971. The ARPANET
has been an operational service for at least 10 years. Even while it
has provided a reliable service in support of a variety of computer
research activities, it has itself been a subject of continuing
research, and has evolved significantly during that time.
In the past several years ARPA has sponsored additional research on
computer networks, principally networks based on different underlying
communication techniques, in particular, digital packet broadcast
radio and satellite networks. Also, in the ARPA community there has
been significant work on local networks.
It was clear from the start of this research on other networks that
the base host-to-host protocol used in the ARPANET was inadequate for
use in these networks. In 1973 work was initiated on a host-to-host
protocol for use across all these networks. The result of this long
effort is the Internet Protocol (IP) and the Transmission Control
These protocols allow all hosts in the interconnected set of these
networks to share a common interprocess communication environment.
The collection of interconnected networks is called the ARPA Internet
(sometimes called the "Catenet").
The Department of Defense has recently adopted the internet concept
and the IP and TCP protocols in particular as DoD wide standards for
all DoD packet networks, and will be transitioning to this
architecture over the next several years. All new DoD packet
networks will be using these protocols exclusively.
The time has come to put these protocols into use in the operational
ARPANET, and extend the logical connectivity of the ARPANET hosts to
include hosts in other networks participating in the ARPA Internet.
As with all new systems, there will be some aspects which are not as
robust and efficient as we would like (just as with the initial
ARPANET). But with your help, these problems can be solved and we
Postel [Page 1]
RFC 801 November 1981
NCP/TCP Transition Plan
can move into an environment with significantly broader communication
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 [Page 2]
RFC 801 November 1981
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