Hi Harald,

On 09/29/2016 10:01 AM, Harald Welte wrote:
> This might be off topic, but AFAIR there are PPP type PDP contexts where not raw IP, but actual PPP frames are transmitted over GPRS inside SNDCP/LLC. Not sure if any operators use that, but its perfectly valid.
>

Yes, I think this was introduced in Release 7.  However, it would 
require the use of "PPP" pdp type in CGDCONT, not "IP".  Also, for EPS 
contexts I don't believe that "PPP" type is possible (nor wanted, as 
you'd fry your CPU keeping up with the high-bandwidth connection). 
Probably a legacy feature that might still be used in very narrow 
circumstances.  I've certainly never seen it used in practice.

> In this case PPP doesn't terminate in the modem, so "hardware" support should be irrelevant.
>

True.  But I'm probably missing your point.  PPP packet compression is 
still an optional protocol feature, so it should not preclude 
interoperability.

Regards,
-Denis