Re: [lwip-users] Recovering from network outage

[address@hidden]

Am 13.04.2021 um 08:08 schrieb Rod Boyce:
> Jeff,
>
> It sounds like you are using Ethernet this being the case you can detect
> link-up and link-down from the Ethernet PHY.
>
> This means that you can poll the Ethernet PHY for link status and either
> take networking down when Phy is disconnected or bring networking up
> when Phy is connected.

While you can check if the phy is reconnected (hint: use the link status
callback provided by lwIP), this will not be of much use, as you could
well get disconnected behind the first (or any) switch (so your own link
status always stays up).

In this case, there's really no other option than to poll for a
connection and wait for it to succceed. Ideally, you'd combine this with
a low-enough (but not too low) connection timeout.

Regards,
Simon

>
>
> Hope that helps.
>
> Rod
>
>
> On 12/04/2021 21:03, Thompson, Jeff wrote:
>>
>> How can I recover from a network outage? I leave the cable from my
>> system to the network switch connected, but pull the cable from the
>> network switch to the cloud. Detecting that the server I was talking
>> to is no longer talking is easy enough, but how do I recover? I’m
>> using a plain old socket to make the connection, and
>> lwIP_send/lwIP_recv) for data transfer of an HTTPS GET request.
>>
>>  
>>
>> I start up a timer that expires if there is no server response after a
>> minute; much more than enough, I’m told. But what then? Can the timer
>> callback do anything to make lwIP_send or lwIP_recv return to the
>> calling task, preferably with an error?
>>
>>  
>>
>> *Jeff Thompson* |  Senior Electrical Engineer-Firmware
>> +1 704 752 6513 x1394
>> www.invue.com <www.invue.com>
>>
>>  
>>
>>
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>
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