From owner-freebsd-hackers Sat Jul 17 17:52:50 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from apollo.backplane.com (apollo.backplane.com [209.157.86.2]) by hub.freebsd.org (Postfix) with ESMTP id 5FABD14C3C for ; Sat, 17 Jul 1999 17:52:47 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.9.3/8.9.1) id RAA86335; Sat, 17 Jul 1999 17:50:36 -0700 (PDT) (envelope-from dillon) Date: Sat, 17 Jul 1999 17:50:36 -0700 (PDT) From: Matthew Dillon Message-Id: <199907180050.RAA86335@apollo.backplane.com> To: Duncan Barclay Cc: hackers@FreeBSD.ORG, crypt0genic , Bill Paul , Vincent Poy Subject: Re: poor ethernet performance? References: Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :On 17-Jul-99 Matthew Dillon wrote: :> :> Obviously you don't get square waves going down the wire - But it is :> still a digital communications protocol. :> :> -Matt : :However the physical layer, i.e. the cable, is analogue and the discussion was :about cables. To carry your reasoning a bit further - a digital :cellular phone system is not an RF/Wireless system because the data is digital. :I hope we agree that it is! : :Duncan Duncan, the entire physical world is an analog medium. Well, not including quantum mechanical effects anyway. Even the photons running down *FIBER* are essentially analog signals - because the lasers cannot be turned on and off instantly. The difference between treating the medium as analog or digital is that when you treat it as digital you quantize it well above the noise floor and treat errors seriously - the idea is to recover the data exactly as it was sent. When you treat the medium as analog, you either do not quantize it at all, or you quantize it close to the noise floor and ignore the errors. The recovered data does not have to exactly match what was sent. -Matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message