Appendix A - Network Connection Protocol to SRI-Network Information Center
1. Initial Connection Protocol
Connection establishment to NIC is identical to that presented in Section II of NWG/RFC 80 NIC (5608,); it is reproduced here:
Telnet contacts NIC
NIC <- user site
RTS <us> <l> <p>
NIC logger is socket 1
user site <- NIC
STR <l> <us> CLS <l> <us>
if accepted
CLS <l> <us>
if rejected
assuming NIC accepts
user site <- NIC
STR <ss+l> <us>
RTS <ss> <us+l> <q>
NIC receives text thru local socket ss from remote
socket us+l via link q
assuming user site accepts
NIC <- user site
STR <us> <ss+l>
RTS <us+l> <ss> <r>
NIC sends text to remote socket us thru local socket
ss+l via link r
.
.
.
user site <- NIC
ALL <q> <space>
.
.
.
NIC <- user site
ALL <r> <space>
2. Connection Breaking Protocol
A CLS trade is made between the NCPs for each of the two connections as per Document #1 NIC (5143,).
We may decide to put a time-out into the NIC connections such that no interaction for some (as yet unspecified) "reasonable" length of time will result in a CLS-out of the connections being initiated by NIC.
3. Third Level Protocol
The first 8 bits received by NIC thru socket ss should be the message data type designating that an 8-bit ASCII stream follows, as per NWG/RFC #63, NIC (4963,).
I.e., the first 8 bits are 00000001
The first 8 bits received by Telnet thru socket us will also indicate a message data type of 1. Each network message should have an integral multiple of 8 bits. If a network standard is established different from the suggestion of NWG/RFC #63, NIC (4963,), then we would change this protocol to conform.
NIC will have NCP-generated interrupts disabled, i.e.,
INR will be ignored
INS will not be sent to the remote host
4. NLS(NIC) Character Conventions of Interest to Telnet
Echoing can either be under control of NLS(NIC) or under control of the user site. When we refer to echoing below, we mean under control of NLS(NIC). When echoing is handled by the user site we would expect the user to set the NLS(NIC) output conventions to conform to the echoing conventions at his site. NLS(NIC) assumes echoing is handled by the user site unless explicitly commanded otherwise.
Format affecting control characters:
- horizontal tab
- spaces to next (user definable) stop on both echoing and output.
- if during literal input, enters file as ASCII '11.
- form feed
- carriage return and (user definable) appropriate number of line feeds on echo and output.
- If during literal input, enters file as ASCII '14
- vertical tab
- carriage return and (user definable) appropriate number of line feeds on echo and output
- if during literal input, enters file as ASCII '13
- carriage return
- carriage return followed by line feed on echo and output
- if during literal input, enters file as EOL (see below)
- line feed
- line feed on echo and output
- enters file as ASCII '12 on literal input
- EOL (end of line)
- presently ASCII code '37
- carriage return followed by line feed on echo and output
- if during literal input, enters file as ASCII '37
- If the user's system automatically appends a LF to a CR before sending it to Telnet or converts CR to some EOL code not ASCII '37, we would expect Telnet to send NLS(NIC) just a CR or ASCII '37. If we receive CRLF, then on output we will send CRLFLF.
5. NLS(NIC) Interrupt Attention Convention
A (user definable) ASCII code in the text input stream is used to abort the executing process and return control to the main NLS(NIC) command processor.
This code is presently DEL (ASCII '177).
- Escape to the NIC monitor: No escape is required as all operations needed for use of the NIC can be performed within NLS(NIC).
- Character Set: We strongly recommend that the Telnet process be able to generate by some set of keying conventions all 128 ASCII codes. Use of NLS(NIC) will probably feel most comfortable from a device with upper and lower case graphics, although we can provide service to single case devices. We can provide a useful service if the full ASCII set cannot be sent, but would like to minimize the special cases we have to handle. Sites which cannot provide the full ASCII set should contact us.
Figure 1 - Telnet Connection:
+----+ |
| | Server |
| | Program |
| | |
+----+ |
^ | |
| v |
+----+ Terminal |
| | control |
| | software | SERVER
| | and | SITE
+----+ possibly |
^ | hardware |
| v |
+----+ |
| | |
| | NCP |
| | |
+----+ |
^ | |
| v |
. .
. .
. .
. .
^ |
| v
+----+ |
| | |
| | NCP |
| | |
+----+ |
^ | |
| v |
+----+ |
| | |
| | Telnet |
| | |
+----+ |
^ | | USER
| v | SITE
+----+ Terminal |
| | control |
| | hardware- |
| | software |
+----+ |
^ | |
| v |
+----+ |
| | User |
\ | terminal |
\--+ |
[ This RFC was put into machine readable form for entry ] [ into the online RFC archives by Tony Hansen 08/08 ]