Date: Tue, 19 Mar 1996 06:10:18 -0800 From: "Jordan K. Hubbard" <jkh@time.cdrom.com> To: Greg Lehey <lehey.pad@sni.de> Cc: hackers@freebsd.org (FreeBSD hackers), isdn@muc.ditec.de (Distribution List; FreeBSD ISDN) Subject: Re: ISDN: "modem" or board? (Was: Microsoft "Get ISDN"?) Message-ID: <1434.827244618@time.cdrom.com> In-Reply-To: Your message of "Tue, 19 Mar 1996 13:52:53 %2B0700." <199603191255.NAA08040@nixpbe.pdb.sni.de>
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> 1. Speed of a connection. Some people say "the bottleneck is the B > channel, so you can use async instead". Well, yes, assuming your > machine isn't doing anything else. To run 2 B channels flat out, > you need a 230 kb/s line, which with standard el cheapo 16550As You, uh, would? 64+64 = 128Kb/s using my own calculator! :-) > ISDN board, the software talks directly to the D channel. On an > ISDN "modem", you need first to establish (serial) connection with > the "modem", it then needs to interpret your commands and talk to > the D channel. This is bound to take longer, but the question The difference is not noticable at all with my own pair of TAs - from connection to the serial port to a login prompt on freefall takes all of 1-2 seconds. The lengthy bit is the chat script login and SLIP negotiation phase - something I couldn't avoid with a card, I think. > 4. Price. I think some people have not read the messages carefully. > I just ordered another batch of boards for DM 133 each, about $90. Lucky you - you can even get them! :-( I've had mine on order from Teles for 5 months now. Still no availability in the U.S. I looked around avidly for a pair of boards when I first got my ISDN line and finally punted in favor of the two $349 ADTRAN TAs that were available Right Now. The ADTRAN TAs are also nice in that they do channel bonding transparently. You just configure the modem for bonding mode 1 and it automagically makes two outgoing calls and bonds the B channels together for a single "fat pipe". I've talked with Helmuth a little about this and it doesn't look like it's anywhere near as easy to do with the TELES cards, though I may have misunderstood him. > - He mentions CAPI. For those of you who didn't want to ask, CAPI is > a German API for ISDN boards. To the best of my knowledge, the only Oh yeah, the TAs also support standard Hayes dialing. I'm not looking forward to figuring out how to use the dialer interface for the boards. Don't get me wrong - I STILL want a pair of boards because I want to have a full 128K/sync connection and get that last 25% of performance out of the line, but I think that for some people a pair of TAs is the most no-brainer, plug-it-in-and-go-today solution you can buy. Jordan
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