Date: Thu, 14 Mar 1996 10:10:38 -0600 (CST) From: Joe Greco <jgreco@brasil.moneng.mei.com> To: lehey.pad@sni.de (Greg Lehey) Cc: cmlambertus@ucdavis.edu, hackers@freebsd.org, jkrause.padg@sni.de Subject: Re: Microsoft "Get ISDN"? Message-ID: <199603141610.KAA22055@brasil.moneng.mei.com> In-Reply-To: <199603140810.JAA25804@nixpbe.pdb.sni.de> from "Greg Lehey" at Mar 14, 96 09:06:28 am
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> I don't like "ISDN modem"s for a number of reasons: > > 1. They're more expensive How do you figure? $300-$400 isn't bad. You pay $225-$250 for a decent V.34 modem... > 2. In my experience, they're *much* less reliable. I've _never_ seen a failure. On the other hand, the Combinet ethernet bridge stuff we use at work is tempramental, unreliable, and difficult to configure. I generally point people away from that particular solution. > 3. They require to be connected by an async line. Considering that > 128 kb/s ISDN translates to 160 kb/s async, it's evident that > you can't keep up the same speed. In addition, conventional "El > Cheapo" serial interfaces lose data at this speed. True (well, I haven't seen lossage using 16550's, but anyone using 16450's deserves what they get). > 4. You can't run raw IP over them, mainly because of (3). I don't see people running "raw IP" over sync lines, either. It's generally run via PPP or Cisco or some other protocol.. you can certainly run PPP or SLIP over an async ISDN connection as well. > 5. You can't use them for connect on demand. The board solution can > allow the system to disconnect after a certain idle time, and then > reconnect when another packet arrives (from either side). Eh, really????? Wow. And here I thought iijppp had these features built in. Silly me. ;-) > 6. I'm not sure about this, but I believe call setup is slower. On a > direct connect board, call setup is round 2 seconds. This is > particularly important for point (5). Call setup for a dual-channel ISDN link around here is about two seconds, maybe three, but it's doing more work than a single link. I have no idea why you think a direct connect board would be faster. You are being limited by the rate at which you can chat with the switch and how fast the switch can set up the call (possibly involving more than one switch). > > You can also get ISDN modems that plug into your serial port which > > are then used as point to point links (ppp, slip). > > As the Germans say, you can also put rivets in your ears, hang slices > of sausage on them, and claim you're a dachshund. I guess I don't understand what your problem with this is. ISDN terminal adapters were _designed_ specifically to do these sorts of things, and in my experience they are more reliable and less tempramental than analog modems. In my opinion, it's always great when you can leverage off of pre-existing technology. The TA's play right into the fact that support for serial devices like modems is widespread and well tested. It's a zero effort solution.. ... Joe ------------------------------------------------------------------------------- Joe Greco - Systems Administrator jgreco@ns.sol.net Solaria Public Access UNIX - Milwaukee, WI 414/546-7968
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