Date: Fri, 28 Jun 1996 13:41:22 -0400 From: "Jacob M. Parnas" <jparnas@jparnas.cybercom.net> To: "Andrew V. Stesin" <stesin@elvisti.kiev.ua> Cc: msmith@atrad.adelaide.edu.au (Michael Smith), Kevin_Swanson@blacksmith.com, hardware@freebsd.org, bsdi-users@bsdi.com Subject: Re: muliport boards - building a PPP dialup server Message-ID: <199606281741.NAA04008@jparnas.cybercom.net> In-Reply-To: Your message of Fri, 28 Jun 1996 13:27:19 %2B0300. <199606281027.NAA04222@office.elvisti.kiev.ua>
next in thread | previous in thread | raw e-mail | index | archive | help
I'm confused. I thought the 16550 was good up to 115,200 baud, but when ISDN eventually takes over with compression, ~512kbaud will be the norm. I don't know if they can handle that. I've heard of a 16650 to come out that can do better. Its amazing that one of the slowest protocols on the computer is the one that gives most people the most trouble. The UARTs seem to be one step behind as do the motherboard/software companies. I'm of course talking about RS/232 system, which has been a problem with some software at anything over 300 baud at times (even with 9600 baud modems operating at 300 baud. Sun requires a special board at least on my sparc 2. So there's no problem with a 10mbit/sec ethernet, but 1200baud to 1/20 of the original ethernet speed is even on workstations. On the positive side, I'm told that CDA is going to port to BSDI next for the Sportster 128 Kbaud (512kbaud with compression) and should have a beta copy in late July. THey've already done it for Unixware and SCO and possibly Solaris (I think they said they were finishing it up). Anyway, this is a cheap internal card which you can read all about on http://www.usr.com/. I've seen it for $319, CDA said that Bell Atlantic and possibly other companies would sell it for $199 if you bought it at the same time as ISDN service. It does lots of nice things like automatic switching of data from 1 to 2 or vice versa BRI 64 Kbyte data chanels on the fly, Three types of compression (Stac, Ascend and Microsoft). The modem driver costs $95 for Unix. Since its right on the ISA bus, there are no problems with overruns I'm told. Jacob PS. If I were basing a business on modems, I'd make absolutely certain that they all worked at 512Kbaud, at the same time. If you've ever experienced overruns, its not pleasant. Usually the machine kernel panics and crashes the machine, fairly often, or in clusters. Not much fun, especially when you have users that have to deal with it, and are justifyably less than pleased at placing their trust in you. ----- In message <199606281027.NAA04222@office.elvisti.kiev.ua>you write: >Hello, > ># > I want to add an ISA multiport serial card to this server and hang ># > up to 8 serial devices from it. Can you buy a multiport card that has ># > different speed limits on each port? For example, I'd like to have ># > maybe four high-speed connections up to 115.2KBps for user ># > connections, two ports that go to 57.6 KBps max and 2 ports that are ># > only 9600 baud. ># ># Don't bother; just get an 8-port "dumb" serial card with 16550's on it. ># You shouldn't have to pay more than a couple hundred dollars for it, ># and your system will handle a fair number of these ports flat out. > > Seconded 100%. 16 ports are no problem. Speed limitations? > Read man stty :) > ># > Basically, I'm going to be hanging some serial devices from this ># > that I don't need a fast connection for. If I want some ports to go up ># > to 115.2, do they all have to? > ^^^^^^^^^^^^^^^^^^^^ No. > ># > I'm looking to save some money if possible. > > 8x16550 IS The Cheapest Working Solution. > ># > I've seen that some people have have used Digi PC/8 boards for this ># >type of thing? Digi also has "intelligent" models (PC/Xe, PC/Xr, ># >PC/Xem) that have a front-end processor and don't require an interrupt ># >on the computer? Has anybody gotten these "intelligent" boards to work ># >with freebsd 2.1? ># ># Of course, but any "intelligent" serial board will conflict with your ># "save some money" requirement; the cost per port is over double that ># of a "dumb" card, and in your case it's not warranted. > > Not to mention the fact -- at least some models of > Digiboard have a speed limit of 57600; and despite > of their intelligence, I can't tell for sure that 16port Digi > really saves you so much CPU compared to 16x16550. > (Don't know is it a driver problem; but I have seen > a situation recently, when people (using BSDi) are > going back to FIFOed 16550s from Digiboard, because > of... CPU limitations). > ># ># > Kevin_Swanson@BLaCKSMITH.com ># ># -- ># ]] Mike Smith, Software Engineer msmith@atrad.adelaide.edu.au [[ ># ]] Genesis Software genesis@atrad.adelaide.edu.au [[ ># ]] High-speed data acquisition and (GSM mobile) 0411-222-496 [[ ># ]] realtime instrument control (ph/fax) +61-8-267-3039 [[ ># ]] Collector of old Unix hardware. "Where are your PEZ?" The Tick [[ ># > > >-- > > With best regards -- Andrew Stesin. > > +380 (44) 2760188 +380 (44) 2713457 +380 (44) 2713560 > > "You may delegate authority, but not responsibility." > Frank's Management Rule #1. > ------------------------------------------------------------------------------ | Jacob M. Parnas | | IBM Thomas J. Watson Research Ctr. | | Internet: jparnas@jparnas.cybercom.net | ------------------------------------------------------------------------------
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199606281741.NAA04008>