Date: Tue, 26 Jan 1999 22:03:51 -0800 (PST) From: Archie Cobbs <archie@whistle.com> To: andreas@klemm.gtn.com (Andreas Klemm) Cc: archie@whistle.com, eivind@FreeBSD.ORG, isdn@FreeBSD.ORG Subject: Re: I4B support for US ISDN? Message-ID: <199901270603.WAA10563@bubba.whistle.com> In-Reply-To: <19990127061109.A3340@titan.klemm.gtn.com> from Andreas Klemm at "Jan 27, 99 06:11:09 am"
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Andreas Klemm writes: > On Sun, Jan 24, 1999 at 08:06:51PM -0800, Archie Cobbs wrote: > > What do you think of the idea of making i4b express itself as a > > netgraph node? This would be a good thing IMHO. > > Hi Archie, > > what is netgraph ? Netgraph is a networking infrastructure we developed at Whistle. It's been very successful in making it easy for us to implement lots of different protocols, etc. Basically you have processing nodes that connect together (via "hooks") to form a graph. Data flows along edges in the graph, and each node does whatever.. The "web site" (actually an FTP site) is here: ftp://ftp.whistle.com/pub/archie/netgraph/index.html The blurb gives basic overview, describes, how it works, etc. We have our own ISDN implementation that expresses the BRI as a netgraph node. ISDN is a natural application for netgraph. We use a modified mpd (soon to be released) to do PPP. I'd imagine an ISDN system could be structured something like this: o A "BRI" node type expressed by any BRI hardware. Properties.. - Three hooks, "B1", "B2", and "D" - Control message support for PH_ACTIVATE_REQ and PH_DEACTIVATE_REQ o A "Q.921" node type to handle data link operations - A "downstream" hook (this would connect to the "D" hook above) - Upstream hooks for multiple TEI's (connecting to one or more Q.931 nodes) o Several different "Q.931" node types, one for each switch type (or possibly a single node type supporting multiple switch types). These would support control messages corresponding to an application level call control.. ie, dial, answer, hangup, etc. Our existing netgraph node implements a control message API like this. Our current implementation glomms all of the above into a single node, but there's no reason you couldn't separate it out. Then any ISDN hardware device driver that implemented the "BRI" node type could readily be used, etc.. -Archie ___________________________________________________________________________ Archie Cobbs * Whistle Communications, Inc. * http://www.whistle.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message
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