Re: [lwip-users] ppp over serial works with gsm modem sim900d but not working with sim5216j using same controller harware

[Sylvain Rochet]

Hello,

On Wed, Apr 01, 2015 at 03:18:02AM -0700, rohanm wrote:
> hii ,
> 
> i have implemented ppp over serial using gsm modem sim900d. and it works
> fine.device gets ip address properly.
> 
> but when I replaced GSM modem with sim5216j ,ppp not able to established
> connection with sim5216j.
> i am using same code and hardware which used for sim900d implementation.
> 
> so i have monitored gsm modem response for ppp frames,which i found not as
> per protocol.
> 
> for ex.
> 
> sim 900d response for ipcp frame:  
> 7E FF 03 80 21 02 03 00 16 03 06 DF E8 B4 7F 81 06 3B 90 7F 75 83 06 CA 38
> D7 29 1A 39 7E
> 
> sim 5216j response for ipcp frame:
> 7E 80 21 02 0A 00 16 03 06 6A CF 56 68 81 06 3B 90 7F 75 83 06 CA 38 D7 29
> DE 27 7E 
> 
> so as per my knowlege,address byte and control byte i.e. 2nd and 3rd 
> byte of sim 900d response is missing in sim5126j response.

I suppose this is wrong too, accomp (Address/Control compression) is 
only acceptable for IP/IPv6 packet AFAIK, but that's not a big deal.

Anyway, it should works, because we don't care if accomp is enabled or 
disabled in PPPoS input path. (see pppos_input() around PDADDRESS and 
PDCONTROL).

Could you enable PPP debug so we can check what is decoded by the PPP 
stack ?

#define PPP_DEBUG           LWIP_DBG_ON
#define PRINTPKT_SUPPORT    1

Sylvain


And please stop using Nabble, dammit.

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