From 4bfd864f10b68b71482b35c818559068ef8d5797 Mon Sep 17 00:00:00 2001 From: Thomas Voss Date: Wed, 27 Nov 2024 20:54:24 +0100 Subject: doc: Add RFC documents --- doc/rfc/rfc1090.txt | 227 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 227 insertions(+) create mode 100644 doc/rfc/rfc1090.txt (limited to 'doc/rfc/rfc1090.txt') diff --git a/doc/rfc/rfc1090.txt b/doc/rfc/rfc1090.txt new file mode 100644 index 0000000..67fd3c1 --- /dev/null +++ b/doc/rfc/rfc1090.txt @@ -0,0 +1,227 @@ + + + + + + +Network Working Group R. Ullmann +Request for Comments: 1090 Prime Computer, Inc. + February 1989 + + + SMTP on X.25 + +1. Status of this Memo + + This memo proposes a standard for SMTP on the virtual circuit + facility provided by the X.25 standard of the CCITT. + + Distribution of this memo is unlimited. + +2. Introduction + + The possibility of using the X.25 virtual circuit (ISO level 3) + directly for SMTP is mentioned in RFC 821 ("SIMPLE MAIL TRANSPORT + PROTOCOL"), in appendix D. It suggests that "a reliable end-to-end + protocol such as TCP be used on top of X.25 connections". This was + undoubtedly true considering the general reliability of the PSDNs at + the time (1981). The service is now (in 1989) reliable enough to + allow practical direct use of the virtual circuit service. + + The procedures given here have proven to be successful in extensive + production use, involving 24 PSDNs in 22 different countries. The + resulting service is economical even using some of the more expensive + PSDNs. Operation over private X.25 connections and X.25 LANs has + also proven successful. + + An X.25 virtual circuit (VC) is opened for each SMTP session. The + full duplex channel provided by the VC is used for the session. The + VC is then closed, normally by the calling side. + +3. Protocol ID and Call User Data + + The first four octets (bytes) of the Call User Data Field, which are + commonly used as a protocol identifier, or PRID, should be (hex) + C0F70000. (In decimal, 192 247 0 0.) + + Implementations should, however, provide the ability to configure the + call user data on a per-address basis, including the protocol ID + field. + +4. Data stream + + The SMTP data is divided into (streamed into) packets in any way the + sending side prefers. Sequences with the M bit (more data) set are + + + +Ullmann [Page 1] + +RFC 1090 SMTP on X.25 February 1989 + + + encouraged, and may be up to 2048 bytes in total length. + + It is recommended that SMTP commands and responses be sent as single + packets, or single more-data sequences, if only to facilitate + debugging the protocol. This is not a requirement. + +5. Qualified data + + Packets with the Q bit set and interrupt packets are not used, and + should be ignored if received. + +6. Circuit resets + + If a level 3 circuit reset is received, the VC should be cleared, and + the SMTP connection attempted again. The retry may be after some + delay, and may be with different call facilities. + +7. Call facilities + + Any negotiable features selected by the X.25 call request facilities + field may be used. Implementations should provide the ability to + specify facilities for each called address. + +8. Character code + + The character code used on X.25 is the full ASCII-8 code, with no + escapes or modifications. Lines are terminated by CRLF (13 10 + decimal). Implementations should, if possible, recognize lines + terminated only by LF (10 decimal). + +9. Closing the connection + + Unlike TCP, X.25 does not provide for synchronous delivery of data in + transit when a clear request is in progress; any packets in transit + are discarded when the VC is cleared. Therefore, on X.25, the SMTP + session layer is closed by the calling side when the Service Closing + message is received, either in response to a QUIT command, or because + the service must shut down. + +10. Timeouts + + SMTP does not normally provide for timing out a session. On X.25, + the following has proven to be effective: + + 10.1. call request + + If a call accept is not received within 100 seconds, or the + Service Ready message is not received within (another) 120 + + + +Ullmann [Page 2] + +RFC 1090 SMTP on X.25 February 1989 + + + seconds, the call should be cleared and retried later. + + 10.2. established + + After the protocol session is established, the circuit should + be cleared if no response is received for 10 minutes. + + 10.3. closing + + After the QUIT command is issued, the timeout should be + shortened to 20 seconds. This will sometimes cause an + ungraceful exit, but this will not affect the SMTP transactions + already completed. + + 10.4. clearing + + When the X.25 Clear Request packet has been sent, the VC should + be timed out in accordance with the X.25 protocol + specification. + + 11. Other features + + Other features of X.25, such as permanent virtual circuits and + D bit selection, are not used. + +References + + [1] Postel, J., "Simple Mail Transfer Protocol", RFC 821, USC + Information Sciences Institute, August 1982. + + [2] CCITT Recommendation X.25, "Interface Between Data + Terminal Equipment (DTE) and Data Circuit-Terminating + Equipment (DCE) for Terminals Operating in the Packet + Mode and Connected to Public Data Networks by Dedicated + Circuit", International Telegraph and Telephone Consultative + Committee, Fascicle VIII.3, Geneva, 1976; amended at + Geneva, 1980 and Malaga-Torremolinos, 1984. ("Red Book") + +Author's Address + + Robert Ullmann 23A-32 + Prime Computer, Inc. + Technology Drive + Milford, MA 01757 + + Phone: +1 508 478 8600 x1736 + + Email: Ariel@Relay.Prime.COM + + + +Ullmann [Page 3] + +RFC 1090 SMTP on X.25 February 1989 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Ullmann [Page 4] + \ No newline at end of file -- cgit v1.2.3