Date: Thu, 19 Oct 1995 13:07:20 -0700 From: David Greenman <davidg@Root.COM> To: dennis@etinc.com (dennis) Cc: Joe Greco <jgreco@brasil.moneng.mei.com>, hackers@freebsd.org Subject: Re: Bragging rights.. Message-ID: <199510192007.NAA29801@corbin.Root.COM> In-Reply-To: Your message of "Thu, 19 Oct 95 16:03:35 EDT." <199510192003.QAA28405@etinc.com>
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>>> 115k minus 20% async overhead.....Mostly I've heard about 70k or so for >>> async links....If you don't think that 20-30% is worth an extra hundred >>> dollars, then I guess you're entitled to that. It is, however, a >consideration. >> >>Really??!! >> > >>I had a 386DX/40 that routinely chatted with a 386DX/16 at 115200 (UUCP over >>TCP/IP as a SLIP connection) and consistently hit > 10.5K/sec -- the number >>ran around 11K/sec during non-peak times here at MEI, and I attribute the >>difference to our network rather than any of the FreeBSD boxes involved (our >>network traffic peaks at wire saturation at times, and never falls below >>10%). > >90K still isn't 128k though??!!!!! So what does this have to do with ISDN, >anyway? You realize, of course, that you're going through a Telephone switch >digitally with ISDN..... Let me add a bit of sanity to this part of the discussion. 115200 baud async will give you about 11.52Kbytes/second if you have no packet overhead. 115200 baud sync will give you 14.40Kbytes/second if you have no packet overhead. Why? Because we're talking bits - async is 8 data bits plus 1 start and 1 stop bit...10 bits. With synchronous serial, it's just 8 data bits. So sync always has the potential to give you 25% more bytes throughput at the same bit rate compared to async. Now with sync you'll also be running at a faster bit rate (128000bits/sec). This is 16Kbytes/second. This is 38.9% faster. -DG
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