Re: [lwip-users] PPPoS: ppp session disconnect if hit bad fcs for LCP packet

[Axel Lin]

2017-07-01 12:28 GMT+08:00 Axel Lin <address@hidden>:
> 2017-07-01 0:47 GMT+08:00 Patrick Klos <address@hidden>:
>> On 6/30/2017 11:18 AM, Axel Lin wrote:
>>>
>>> It's not easy to hit this issue, usually it needs to run for a couple
>>> hours or more than one day.
>>> But the symptom seems to be the same.
>>>
>>> BTW, my device always keep sending data to LTE through pppos.
>>> I'm wondering why the bad fcs usually happened on LCP packet.
>>
>>
>> Can you dump out the failing LCP packet?  And maybe a few of the preceding
>> packets?  What kind of connection do you have between the micro running lwip
>> and the LTE modem?  Is there any way to tap that serial link and watch it to
>> compare that against your micro's serial receive routine?
> Hi Patrick,
>
> I cannot tap the serial link now, but I will try to dump out the failing 
> packet.
> My device keep sending data to a http server.
> i.e. compare to the the total traffic count, LCP packet is pretty small count.
> So i'm wondering why the bad fcs usually happens on LCP packet.
> I have to test it more times.

The bad fcs issue I hit is because of running out of pbuf.
pppos_input[0]: NO FREE PBUFS!
pppos_input[0]: Dropping bad fcs 0xceb3 proto=0xb7

I'm testing again after increasing number of PBUF_POOL.