-----Original Message----- From: owner-postfix-us...@postfix.org [mailto:owner-postfix-us...@postfix.org] On Behalf Of Glenn English Sent: Saturday, 31 August 2013 12:52 AM To: postfix-users@postfix.org Subject: Re: newbie check Was [Re: port 25 submission settings sanity check]
On Aug 30, 2013, at 7:07 AM, Terry Gilsenan wrote: >> As attachments get larger, and end users use email rather than ftp for file >> transfer for convenience sake, a UDP implementation, perhaps using UDP as a >> data >>streaming channel could become a very useful configuration, and the >> transfer speed over high latency links (think satellite etc) could improve >> immensely. > >I don't think so. As Weitse said yesterday, to run SMTP successfully on UDP, >he'd have to duplicate TCP's back-and-forth to make sure those bits got there, >they >were correct, in the right order, etc. If that were done, you'd be back >at TCP overhead and speed (and reliability). > >Streaming movies is one thing; transfering legal documents and medical records >is another. There are many file transfer systems that use UDP and take care of integrity within the application layer. Many online backup services use UDP, and they do that for reasons of speed. If they couldn't guarantee data integrity then they would be worse than useless. If each UDP segment was prepended with a CRC and sequence number before being sent, then the application at the other end can take care of packet order, and requesting resend of a packet where there is a gap in the sequence numbers. Not trivial perhaps, but certainly not hard. Many applications already do this. ===[Disclaimer]=== This electronic transmission, including any attachments, is confidential, may contain privileged information and should be read or retained only by the intended recipient. If you received this message in error, please delete it from your system and notify the sender immediately. Any review, dissemination or other use of this information by persons or entities other than the intended recipient is strictly prohibited. ===[End]===
