On Fri, 24 Jul 2009 16:12:41 +0200
Oliver Neukum [off-list ref] wrote:

Am Freitag, 24. Juli 2009 14:48:05 schrieb Alan Cox:

quoted

quoted

No, I was thinking of having two full devices, a data channel and a
control channel for devices that really talk AT commands natively.

If the hardware does it great, however for things like a 3G modem you
have the problem that the PPP is over the AT command channel which may
itself be multiplexed. And the muxing in question is *ugly* - sort of
HDLC and LAP-B done wrong.

Well, yes, but we would really like a separate control channel, so we
can query parameters like signal strength, while we do PPP over the data
channel.

Thats the notion of the AT mux stuff - you get multiple AT channels and
you can stuff PPP down one of them. It's still butt ugly.