DragonFly BSD
DragonFly users List (threaded) for 2006-08
[Date Prev][Date Next]  [Thread Prev][Thread Next]  [Date Index][Thread Index]

Re: questions about interfaces

From: Bill Hacker <wbh@xxxxxxxxxxxxx>
Date: Mon, 28 Aug 2006 18:19:00 +0800

David Cuthbert wrote:

Bill Hacker wrote:

David Cuthbert wrote:

Heh... imagine if the loopback interface actually required hardware.

Imagine? 'Remember when' you mean...

It exists because there was a time when hardware *was* required, and one did not always have arms long enough...

I remember using (and still use) this for modems and serial ports (doing local and remote loopback tests), but never in the context of an IP loopback connection. This is probably because all of my experience with IP/TCP/UDP has been on top of a OS+stack that someone else wrote and debugged, running on hardware that wasn't too terribly esoteric.

What eventually became the '7 layer' protocol stack was originally just two when I started.

Baudot, BCDIC, Selectric code, or USASCII as the top layer, and either 20 ma bipolar or 60ma single-ended telegraph wire ELSE RTTY as the PHY layer. 'High-speed' was stuff like the Hewlett-Packard parallel current-loop.

DTMF modems were a big advance. Far more error-free than Bell 103.
And synchronous 9.6 Codex modems were the mainstay of our X.25 and point-to-point frame-relay backbone for Novell 2.X and 3.X servers.

Things moved so slowly in those days, that two of us at opposite ends of the world could agree to swap cable from 56 Kbps NTE to 9.6 Codex dial-ups on a 3-count, and not lose in-process IPX/SPX over HDLC / Frame Relay transfers.

OTOH, unlike my older-yet C&W mentors, I didn't have to learn Morse, Wheatstone Code, or such...


PDA's and Mobile phones are now nearly as fast as the TDDL that kept SAGE NORAD glued together.

*weird* thing is, I don't remember ever once using the Unix loopback interface for testing. I've always had at least an OS/2 box if not two or more BSD boxen or Slackware to test between/among, and tend to run local services on sockets, not IP anyway.

Still - glad it is all available.


[Date Prev][Date Next]  [Thread Prev][Thread Next]  [Date Index][Thread Index]