From owner-freebsd-chat Wed Sep 3 01:24:57 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id BAA28645 for chat-outgoing; Wed, 3 Sep 1997 01:24:57 -0700 (PDT) Received: from nico.telstra.net (nico.telstra.net [139.130.204.16]) by hub.freebsd.org (8.8.7/8.8.7) with SMTP id BAA28636 for ; Wed, 3 Sep 1997 01:24:53 -0700 (PDT) Received: from freebie.lemis.com (gregl1.lnk.telstra.net [139.130.136.133]) by nico.telstra.net (8.6.10/8.6.10) with ESMTP id SAA26497; Wed, 3 Sep 1997 18:24:29 +1000 Received: (grog@localhost) by freebie.lemis.com (8.8.7/8.6.12) id RAA09200; Wed, 3 Sep 1997 17:54:18 +0930 (CST) Message-ID: <19970903175417.21095@lemis.com> Date: Wed, 3 Sep 1997 17:54:18 +0930 From: Greg Lehey To: Mike Smith Cc: FreeBSD Chat Subject: Re: Anyway to get connect speed with usermode ppp/tun0 device? References: <19970903163957.09017@lemis.com> <199709030806.RAA00241@word.smith.net.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.81e In-Reply-To: <199709030806.RAA00241@word.smith.net.au>; from Mike Smith on Wed, Sep 03, 1997 at 05:36:51PM +0930 Organisation: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8250 Fax: +61-8-8388-8250 Mobile: +61-41-739-7062 WWW-Home-Page: http://www.lemis.com/~grog Fight-Spam-Now: http://www.cauce.org Sender: owner-freebsd-chat@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk On Wed, Sep 03, 1997 at 05:36:51PM +0930, Mike Smith wrote: >> (moved to chat) >> >> On Wed, Sep 03, 1997 at 04:29:44PM +0930, Mike Smith wrote: >>>> >>>>> The speed is specified as 'baud'; in fact, it's bit per second. >>> >>> It is correct to specify the speed as "baud" in conjunction with a >>> single-wire serial interface. >> >> I suppose you mean a two-wire interface. > > No. A two wire interface can transport four values per baud. That depends how it's modulated. >> Sure, you can use the term >> baud if that's the speed talking about. Here we're talking about a >> 2400 baud interface. It's transferring 38,400 bits per second. > > Not by any definition I can comprehend. You have a single wire serial > interface, clocked at 38,400 transitions per second. Look down the wire. > That is 38,400 baud no matter which way you look at it. To achieve > 38,400 bps at 2400 baud you need a signalling mechanism with 65536 > possible values, or 16 bits of significance. This puts you in the > high-end trellis-encoding market, certainly not on good ol' EIA-232. In the context we're talking about, nobody's talking about good old RS-232. We're talking about a modem link. The bauds only make sense when they're not bits per second; otherwise they're just obfuscation. >> OK, you might say "this interface is between the serial interface and >> the modem". And yes, over this interface the speed is 38,400 baud as >> well as 38,400 bps. But that's \fIvery\fP misleading, and there's no >> need for it. > > I don't understand. stty can only report on the configuration of the > serial port, and it does that correctly. But misleadingly. And for no good reason. > It has no way of knowing what the modem thinks its doing; as I have > already pointed out it is impossible to know what the modem is > "really" doing at any point in time anyway. You said that you didn't know a way to extract the information. That's not quite the same thing. If I could dig my modem docco out of one of this maze of twisted boxes, all alike, I could check on that, but wasn't there an S register that contains this information? Greg