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

[Axel Lin]

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?

I got a dump of the data when bad fcs happened. (This time is "IP"
rather than "LCP")
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

I think the complete packet is:

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

the bad fcs is a7c5
Is there any thing wrong in above received data?