Date: Sat, 9 Dec 1995 14:06:50 -0600 (CST) From: Joe Greco <jgreco@brasil.moneng.mei.com> To: tom@uniserve.com (Tom Samplonius) Cc: winter@jurai.net, sreid@edmbbs.iceonline.com, freebsd-isp@freebsd.org Subject: Re: Hardware for ISP / WWW server Message-ID: <199512092006.OAA22400@brasil.moneng.mei.com> In-Reply-To: <Pine.BSF.3.91.951209111123.17129D-100000@haven.uniserve.com> from "Tom Samplonius" at Dec 9, 95 11:19:17 am
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> On Sat, 9 Dec 1995, Joe Greco wrote: > > > > > 28.8 kbps modems for dial-up > > > > > > Run dialup from a terminal server. A Livingston portmaster is a great > > > box and has a very hackable security server. (Um... no, rather its easy > > > to modify to suit your needs) > > > > Ewww, no way. > > > > A Livingston Portmaster has some pretty gnarly drawbacks: > > > > 1) has problems with subnets > > None, that I've seen. And I run quite a few sub-nets from various > Portmasters. In fact, my house is connected by one. Tried running one on a non-class-C subnet? > > 2) requires you to waste IP addresses due to the way the thing reserves > > addresses for dropped connections > > Huh? You need 30 addresses for 30 ports. There was a reported bug, > that said that the unit would sometimes use 31 or 32. But still hardly a > waste. Not a bug, a feature. The Portmaster reportedly will try to "hold on" to a connection pending a reconnect, but on a busy dial in pool you need to reserve more like 40 addresses minimally. > > 3) in the case of dropped connections totally bungles the way its handled > > I haven't seen this either. This is directly related to 2)... I recently tracked a bunch of hanging processes out at Exec-PC to this very problem. The Portmasters do something strange (not quite sure what since I didn't have a network sniffer) that appears to make FreeBSD's TCP/IP think that the connection is still out there somewhere... and they have had other problems with this "feature" as well. > > 4) isn't really all that flexible > > Not especially. But what it does, it does well. > > > 5) etc (my mind can't think this morning) > > > > I deal with sites that use FreeBSD as terminal servers and sites that use > > Portmasters as terminal servers. Invariably the sites with Portmasters have > > all sorts of bizarro hacks in place to try to get around various problems > > and limitations that these stupid devices seem to cause and/or impose. > > > > If you want a "real" terminal server, buy an Annex. > > A Portmaster can run all ports with PPP at 115,200 baud continous. Try > that on an Annex. Guess it depends which Annex.. > > If you want a more flexible solution than either of these two, go get a > > dedicated FreeBSD box. With the price of a 486DX4/120 motherboard being > > around $200, 16MB of RAM for about $500, and a 16 port BocaBoard for about > > $250, you can make a really reasonable terminal server quite easily. > > The problem is, is that PC serial hardware will never give you > performance of a terminal server. I would think that you could get pretty decent performance out of a high end 486, which are dirt cheap. Or perhaps a Specialix card, if need be... and to be quite honest, I've never seen an ISP where all ports are running PPP at 115,200 baud continuous. I'm often out at Exec-PC, and they're a large Portmaster shop (13? portmasters on the 390 lines in their Milwaukee POP). Most of their lines are connected whenever I look, yet I only see bits of bursty data here and there. The need for a terminal server to run 115200 on all ports simultaneously is marketing bullshit. With 28.8K modems and most graphics being fairly compressed, I would be suprised if the average CPS on a maxxed out port exceeded 4000cps, and at maybe 20% duty cycle under "heavy" traffic conditions, for 16 ports that's 13Ktotal/sec or for 32 ports that's 25Ktotal/sec, which is roughly what I have observed sio to be capable of on a 386DX/40 (two 230.4K serial ports, 1 in use at 22K/sec, 1 in use with a 28.8K modem at around 3K/sec). I suspect a 486DX4/120 would be capable of maybe 5x or 6x this sort of throughput before the CPU got noticeably busy. But of course you've already saturated your 56Kb line several times over at 25KB/sec, or to put it another way, you could maybe shoehorn six 32 port terminal servers onto a T1 at the data rates I have suggested before saturation occurs. For your average ISP, this is probably a much-more-than-adequate solution. And of course with FreeBSD you can go down to the corner store for spare parts, and you get the source. What more could you ask for? I refuse to be a victim of Livingston propaganda :-) ... Joe ------------------------------------------------------------------------------- Joe Greco - Systems Administrator jgreco@ns.sol.net Solaria Public Access UNIX - Milwaukee, WI 414/342-4847
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