Date: Wed, 17 Oct 2001 14:06:00 -0200 From: Sergio de Souza Prallon <prallon@tmp.com.br> To: Chris Knight <chris@aims.com.au> Cc: guy@traverse.com.au, freebsd-isdn@freebsd.org Subject: Re: NetJet-S and DOV Message-ID: <20011017140600.C21633@tmp.com.br> In-Reply-To: <004301c155e1$8007ec50$020aa8c0@aims.private>; from chris@aims.com.au on Tue, Oct 16, 2001 at 12:25:52PM %2B1100 References: <004301c155e1$8007ec50$020aa8c0@aims.private>
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On Tue, Oct 16, 2001 at 12:25:52PM +1100, Chris Knight wrote: > Howdy, > > We're looking at using the NetJet-S in some FreeBSD servers, but > unfortunately the driver according to Traverse's Website doesn't support > data-over-voice (DOV). What would be required to add DOV capability? I'm > happy to write the code, I'm just not sure where to start. > > Regards, > Chris Knight > Systems Administrator > AIMS Independent Computer Professionals > Tel: +61 3 6334 6664 Fax: +61 3 6331 7032 Mob: +61 419 528 795 > Web: http://www.aims.com.au > Hi, I wrote this driver for my personal use here in Brazil. Here, the ISDN B-channels are 8-bit clean. If I understand Traverse's tech staff, DOV consists in declare in the call-setup (in the D-channel) packet that you want the B-channel to be Voice Capable instead of Data Capable. That was because of diferent charge prices made by some of the Telcos. Unfortunately, most of the terminal servers in use in Australia are Ascend and they have a `feature' that if they receive a Voice call, they only take 7 out of every 8 bits of the traffic (because Voice in America is sampled with 7 bits) EVEN IF THEY CARRY HDLC FRAMED DATA. So, the DOV capability would be to be able to call a given phone number setting the Bearer type to Voice (something to be hacked in the layer3 and isdnd I think) and select to operate in 7 or 8 bit HDLC. That would require a new version of the HDLC_ENCODE and HDLC_DECODE macros in i4b_hdlc.h that were able to work with 8bit bytes but with a payload of 7bits. This, I think is the hard part: these macros were very cleverly designed by the previous IHFC author. They are very fast and lean, but are somewhat hard to fiddle with. May be you can start with a trivial, a-bit-at-a-time version of them (like the Linux driver do) to have the project going, and then, after having all the rest up and running, try to patch the original HDLC macros. Hope this helps. -- Prallon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message
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