Telnet Protocol-a proposed document(1)

　　Network Working Group T. C. O'Sullivan

　　Request for Comments: 137 Raytheon

　　NIC 6714 30 April 1971

　　TELNETProtocol

　　This is a request for comment and is being distributed in advance of　the Atlantic City meetings for review and comment prior to or during　discussions on TELNET in preparation for issuing an official　document.

　　It is also being distributed so that selected installations planning　to implement early versions of TELNET will have a common basis for　such implementation.

　　others have been incorporated where even though not thoroughly　cleared with all meThe proposed document is the result of the work of the committee. It　represents a TELNET protocol felt to be adequate for initial　implementation. A few recent suggestions by committee members and　mbers, the chairman felt that they clarified the　protocol or would tend to simplify implementation but not　substantially change the agreed-upon approach.

　　Readers are referenced to the following previous releases of　information:

　　1. Conventions for Using an IBM 2741 Terminal or a User Console for　Accessto Network Server HOSTS　Joel Winett, RFC110 (NIC #5809)

　　2. Level III Server Protocol for the Lincoln Laboratory 360/67 HOST　Joel Winett, RFC109 (NIC #5808)

　　3. First Cut at a Proposed TELNET Protocol　J. Melvin, D. Watson, RFC97 (NIC #5740)

　　4. ASCII Format for Network Interchange　V. Cerf, RFC20(NIC# 4722)

　　Another RFCwill be distributed prior to the Atlantic City Meetings　containing many of the arguments supporting the proposal.

　　TELNET PROTOCOL

　　A Proposed Document

　　T. O'Sullivan for the TELNET Committee

　　Will Crowther BBN

　　Bob Long SDC

　　John Melvin SRI-ARC

　　Bob Metcalf Harvard

　　Ed Meyer MAC

　　Tom O'Sullivan (Chairman) Raytheon

　　Joel Winett MIT-LL

　　TELNET is a third-level protocol, the function of which is to make a　terminal (or process) at a using site appear to the system or a　process at a serving site as logically equivalent to a terminal　"directly" connected to the serving site. In performing this　function, the protocol attempts to minimize the amount of information　each HOST must keep about the characteristics of other HOSTS.

　　Definitions

　　Protocol Levels (see Figure 1)

　　Level 1

　　HOST-IMP protocol specified by BBN in NIC 5735, Specifications　for the Interconnection of a HOST, and an IMP (BBN Report 1822)

　　Level 2

　　HOST-HOST protocol performed by NCPs as described in Document　Number 1 (NIC 5413) and subsequent amendments, see RFC107(NIC　#5806)

　　One view of the NCP's function is that it takes information　from the net and routes it to receiving processes via　mechanisms internal to each HOST; conversely, processes use　the NCP, via internal system calls, to have information　routed to other processes in the net (via the other　processes' NCPs).

　　Level 3 (see Figure 2)

　　Level 3 is, by definition, the place to which and from which　the NCP communicates internally in its own host.

　　This level may be equivalent to the user process level in　some systems, but this may not be the case in all systems.

　　In using sites, the TELNET process operates at this level.

　　In serving sites, the TELNET server operates at this level.

　　Initial Connection Protocol (ICP)

　　An agreed-upon sequence of level 3 exchanges between two processes　which is, in general, used to synchronize the dialogue between the　processes, e.g., RFC80(NIC #5608) #1.

　　Serving Site

　　The HOST into which the TELNET process is directing the user's　keyboard input and from which the TELNET process is receiving　control information and data effecting the user's terminal. At　the serving site, a TELNET server is executing.

　　Using Site

　　The HOST in which the TELNET process is executing.

　　Sending Site

　　The HOST transmitting data, could be either using site or serving　site.

　　Receiving Site

　　Converse of sending site.

　　User

　　The person or process "driving" the TELNET process.

　　In providing services the TELNET protocol will use established　network conventions, specifically the Network Control Program, and　Initial Connection Protocol referenced in the above definitions.

　　The TELNET protocol provides for a Network Virtual Terminal (NVT)　through which users may transmit and receive data over connections　between the using site and the serving site.