lowen at pari.edu
Thu Feb 3 16:25:14 CST 2011
On Thursday, February 03, 2011 03:59:56 pm Matthew Palmer wrote:
> On Thu, Feb 03, 2011 at 03:20:25PM -0500, Lamar Owen wrote:
> > FTP is a in essence a peer-to-peer protocol, as both ends initiate TCP
> > streams. I know that's nitpicking, but it is true.
> So is SMTP, by the same token. Aptly demonstrating why the term "P2P" is so
> mind-alteringly stupid.
Yeah, SMTP between servers is peer-to-peer, since both ends can transmit and both ends can receive, using the same protocol, but in different sessions, unlike FTP, where one session needs two streams, and one originates at the file storage end. But it's also used as a client-server protocol between an SMTP sender and an SMTP receiver, which we commonly call the SMTP server. If it were peer-to-peer at that connection there would be no POP3 or IMAP stacks needed to go get the mail, rather, every workstation would receive its mail directly through SMTP. The peer-to-peer nature of SMTP is broken not by NAT, but by dynamically addressed and often disconnected clients, whether their IP addresses are globally routable or not. Sometimes it would be better to get a five day bounce than for the mail to be delivered to the smarthost but the client never picks it up..... There's a reason POP is the Post Office Protocol, as the addresses are then essentially PO Boxes.....
But, with my apologies to Moe, Larry, and Curly:
"NATagara Falls! Slowly I turned, step by step, inch by inch......" (with a subject of 'quietly' I've been wanting to quote that all thread....) Some are that knee-jerk whenever the Three Letter Acronym That Must Not Be Mentioned is writ large....
More information about the NANOG