Date: Tue, 8 Dec 1998 19:38:36 -0800 From: brian@worldcontrol.com To: bsd@smmc.qld.edu.au Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Does freeBSD2.7 support ISDN? Message-ID: <19981208193836.A15729@top.worldcontrol.com> In-Reply-To: <199812091211.WAA02398@smmcroute.smmc.qld.edu.au>; from bsd@smmc.qld.edu.au on Wed, Dec 09, 1998 at 12:10:45PM %2B1000 References: <Pine.BSF.3.96.981209003433.249A-100000@smmcroute.smmc.qld.edu.au>; <19981207235557.C12623@top.worldcontrol.com> <199812091211.WAA02398@smmcroute.smmc.qld.edu.au>
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On Wed, Dec 09, 1998 at 12:10:45PM +1000, bsd@smmc.qld.edu.au wrote: > Hi Brian, > > I am a lazy typist... FreeBSD > I have a question. Apparently an isdn router can switch on demand 64 k > to 128k. (some or all I don't know) > I am now aware that ppp.conf can be configured to AT commands > for 64 or 128....My question is, can FreeBSD switch on demand as > well? Is there a script to write or does iijPPP somehow support > this? I depends on what you mean by 'switch on demand'. You probably mean when the 1st B channel is saturated you'd like the 2nd B channel to be brought up automatically. I am not aware of a way to do this with the user land ppp (iijPPP). However, I wouldn't doubt that that functionality is transparently supported in some of the ISDN TAs. > Someone mentioned these ...synchronous serial port the 16650 and Hayes ESP are async serial ports. There seems to be a lot of endless confusion about ISDN and serial ports. ISDN is synchronous. If you send 8 bits out and ISDN port, out go 8 bits, which arrive at the other end. If you send an 8 bit byte out an async serial port, the serial port adds a start and a stop bit to the data being sent. Thus each byte sent uses 10 bits "on the wire". At the other end of an async connection the extra bits are stripped off. Thus, with an async serial port running at 115200 bits/second you can really only cram 92,160 data bits/second over the wire. The other 23,040 bits are wasted on the start and stop bits. By using a 230400 bits/second serial port you can cram 184,320 real data bits across this wire per second, which is more than enough to fully utilize the 128,000 bits/second available via a 2B channel ISDN data call. -- Brian Litzinger <brian@litzinger.com> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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