From owner-freebsd-isdn  Thu Oct  1 06:48:22 1998
Return-Path: <owner-freebsd-isdn@FreeBSD.ORG>
Received: (from majordom@localhost)
          by hub.freebsd.org (8.8.8/8.8.8) id GAA20054
          for freebsd-isdn-outgoing; Thu, 1 Oct 1998 06:48:22 -0700 (PDT)
          (envelope-from owner-freebsd-isdn@FreeBSD.ORG)
Received: from theory.cs.uni-bonn.de (theory.cs.uni-bonn.de [131.220.4.161])
          by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id GAA19995
          for <freebsd-isdn@FreeBSD.ORG>; Thu, 1 Oct 1998 06:48:08 -0700 (PDT)
          (envelope-from ignatios@theory.cs.uni-bonn.de)
Received: from cauchy.cs.uni-bonn.de (cauchy.cs.uni-bonn.de [131.220.4.169])
	by theory.cs.uni-bonn.de (8.8.8/8.8.8) with ESMTP id PAA28867;
	Thu, 1 Oct 1998 15:45:50 +0200 (MET DST)
Received: (ignatios@localhost) by cauchy.cs.uni-bonn.de (8.8.8/8.6.9) id PAA24853; Thu, 1 Oct 1998 15:45:49 +0200 (MET DST)
Message-ID: <19981001154548.C24738@cs.uni-bonn.de>
Date: Thu, 1 Oct 1998 15:45:48 +0200
From: Ignatios Souvatzis <ignatios@theory.cs.uni-bonn.de>
To: Hallam Oaks P/L list account <mlnn4@oaks.com.au>,
        "freebsd-isdn@FreeBSD.ORG" <freebsd-isdn@FreeBSD.ORG>
Cc: Andrew Gordon <arg@arg1.demon.co.uk>
Subject: Re: HSCX query
Mail-Followup-To: Hallam Oaks P/L list account <mlnn4@oaks.com.au>,
	"freebsd-isdn@FreeBSD.ORG" <freebsd-isdn@FreeBSD.ORG>,
	Andrew Gordon <arg@arg1.demon.co.uk>
References: <199810011335.XAA27382@mail.aussie.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Mailer: Mutt 0.91.2i
In-Reply-To: <199810011335.XAA27382@mail.aussie.org>; from Hallam Oaks P/L list account on Thu, Oct 01, 1998 at 11:36:23PM +1000
Sender: owner-freebsd-isdn@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.org

On Thu, Oct 01, 1998 at 11:36:23PM +1000, Hallam Oaks P/L list account wrote:
> >software would use a lot of CPU.   If there is hardware HDLC for the B
> >channels but not for the D channel, that would require just the same
> >development effort but would have a much less serious impact on
> >performance since the average data rate on the D channel is extremely 
> >low.
> 
> It may seem to unbelievable (but it's true) that it's the opposite way.
> There is hardware support for decoding the D channel but not for the B 
> channels. As far as the software is concerned, the ASIC is transparent
> for the B's in that it just passes through whatever it receives from the
> ISAC.

This makes sort of sense.

You _need_ HDLC for the D-channel protocols.

You only need HDLC for B-channels, if you use HDLC-base protocols.
Voice data are transmitted raw, so you don't need HDLC necessarily.

Its probably a board for people who want to implement DM 200 functionality
on a DM 2000 machine ;-)

	-is

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-isdn" in the body of the message