3.3.5 Telnet Linemode Option

DISCUSSION:

An important new Telnet option, LINEMODE [TELNET:12], has been proposed. The LINEMODE option provides a standard way for a User Telnet and a Server Telnet to agree that the client rather than the server will perform terminal character processing. When the client has prepared a complete line of text, it will send it to the server in (usually) one TCP packet. This option will greatly decrease the packet cost of Telnet sessions and will also give much better user response over congested or long- delay networks.

The LINEMODE option allows dynamic switching between local and remote character processing. For example, the Telnet connection will automatically negotiate into single- character mode while a full screen editor is running, and then return to linemode when the editor is finished.

We expect that when this RFC is released, hosts should implement the client side of this option, and may implement the server side of this option. To properly implement the server side, the server needs to be able to tell the local system not to do any input character processing, but to remember its current terminal state and notify the Server Telnet process whenever the state changes. This will allow password echoing and full screen editors to be handled properly, for example.