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Re: [lwip-users] ppp over serial works with gsm modem sim900d but not wo
Re: [lwip-users] ppp over serial works with gsm modem sim900d but not working with sim5216j using same controller harware
Wed, 1 Apr 2015 14:25:11 +0200
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
Could you enable PPP debug so we can check what is decoded by the PPP
#define PPP_DEBUG LWIP_DBG_ON
#define PRINTPKT_SUPPORT 1
And please stop using Nabble, dammit.
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