Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!rutgers!ames!ucbcad!ucbvax!DECWRL.DEC.COM!kent From: kent@DECWRL.DEC.COM Newsgroups: comp.protocols.tcp-ip Subject: Re: Dial-up TCP/IP (was interactive SMTP over phone lines) Message-ID: <8705111546.AA16862@armagnac.DEC.COM> Date: Mon, 11-May-87 11:51:45 EDT Article-I.D.: armagnac.8705111546.AA16862 Posted: Mon May 11 11:51:45 1987 Date-Received: Wed, 13-May-87 04:24:12 EDT References: <357@hqda-ai.UUCP> Sender: daemon@ucbvax.BERKELEY.EDU Reply-To: "Christopher A. Kent" Distribution: world Organization: The ARPA Internet Lines: 26 This topic seems to come up every year or so. I have some old messages (from 83) where a few of us discussed this topic. The raw sockets sort of approach seems good, as far as it goes. The real problem seems to be that the IP protocol family (especially TCP) believe in short packet lifetimes (30-60 seconds for TCP open timeout, ~255 seconds total packet lifetime), and this is hard to achieve in a dialnet environment, where it can take 30 seconds to convince a dialer to dial a number and connect the call, much less get logged in, switch the dial port to be an IP link, etc. On top of that, protocols like SMTP count on being able to reach the destination host directly; there's no concept of uucp-ish store and forward in the protocols. This makes opens take even longer; several hosts in succession may have to dial and open connections, depending on the diameter of the net. There are even desirable configurations where it is impossible to have everyone connected at the same time -- say neither hosts A nor B have dialers, but are both periodically polled by C. A and B can never be connected at the same time, thus can't exchange IP packets. That seems to be where the idea of dialup is incompatible with the IP networking model... Cheers, chris