Puzzled about PPP, LCP and IPCP in GPRS....
Posted on 2003-10-29
Is it necessary to use LCP with PPP while dialing in a stand alone mode? I ask this because I have been working with a developer using a wavecom modem, who indicated that during the PDP context activation, the modem was set for auto-connect mode by setting either AT$AREG=2 (or manually activate by sending AT+CGACT=1,1 commands) - you don't have to send the dial string (*99#). This is done automatically inside the modem and it tries to negotiate the PDP context activation with the network. In this case the client would still allow user to enter AT commands even after the PDP context activation is established - unless the modem is setup for PAD mode (which was not the case with the client).
In anycase, the resolve to this situation was for the developers to create a PPP connection by only sending CHAP and IPCP, omitting LCP. Can anyone provide a reason why this would work? In fact does anyone have any information detailing how PPP, LCP, IPCP works in the GPRS environment. I have a feeling I and my colleagues are not understanding the actual procedures.