Discussion of Telnet Protocol (RFC0139)
Original Publication Date: 1971-May-07
Included in the Prior Art Database: 2002-Mar-05
Internet Society Requests For Comment (RFCs)
The attached discussion is an extension of RFC 137, NIC #6717, and is presented to provide useful background to designers and implementers to help them interpret the proposed Protocol and evaluate it in preparation for further discussion at the Atlantic City meetings.
Network Working Group T. O'Sullivan
Request for Comments: 139 Raytheon
NIC: 6717 7 May 1971
Discussion of TELNET Protocol
The attached discussion is an extension of RFC 137, NIC #6717, and is
presented to provide useful background to designers and implementers
to help them interpret the proposed Protocol and evaluate it in
preparation for further discussion at the Atlantic City meetings.
While the views in the discussion represent those of various TELNET
committee members, they should not be interpreted as being the agreed
view of committee. They are the author's understanding of some of
the arguments and background to the PROTOCOL proposed in the TELNET
* See Footnotes to attached discussion for changes to RFC 137.
Discussion of TELNET PROTOCOL
The use of a standard, network-wide, intermediate representation of
terminal code between sites eliminates the need for using and serving
sites to keep information about the characteristics of each other's
terminals and terminal handling conventions, but only if the user,
the using site, and the serving site assume certain responsibilities.
1. The serving site must specify how the intermediate code will be
mapped by it into the terminal codes that are expected at that
2. The user must be familiar with that mapping.
3. The using site must provide some means for the user to enter
all of the intermediate codes, and as a convenience, special
control signals, as well as specify for the user how the
signals from the serving site will be presented at the user
Other schemes were considered but rejected. For example, a proposal
that the using site be responsible to transmit to and from the code
expected by the serving site was rejected since it required that the
using site keep tables of all serving site codes and provide mapping
for each case. The information would require constant maintenance as
new hosts were added to the network.
O'Sullivan [Page 1]
RFC 139 Discussion of TELNET Protocol 7 May 1971
Since it is not known how the current or future sites will specify
the mapping between the network-wide standard code (7 bit ASCII in an
8 bit field) and the codes expected from their own terminals, it
seems necessary to permit the user to cause every one of the 128
ASCII codes, plus (for full user power) selected control signals
(either of a TELNET control nature, or of a special terminal nature
such as break or attention).
There was strong feeling about the importance of the user/system
interface at the using site, but equally strong feeling that this
problem is one of local implementation and should reflect the using
site installation philosophy rather than the subject to network-wide
standards. Some topics of consideration in this area are:
1. How to represent special graphics, not available at the using
site, at the user's terminal.
2. Treatment of upper/lower case problem on TTY 33 and 35.
a. Representing lower-case output.
b. Providing users with shift and shift lo...