Re: [lwip-users] Problems with sending UDP packets in FreeRTOS

[Noam Weissman]

Hi Simon,

I had this problem long ago and as far as I remember packets were not freed
Or that the sending rate was high and eventually it got into no memory.

As you wrote unsent UDP packets will be freed after 5 seconds but if you send a 
packet 
every 100ms or so and only have 20-30 buffers 5 seconds will not solve the 
error.

BR,
Noam.

-----Original Message-----
From: lwip-users [mailto:address@hidden On Behalf Of Simon Goldschmidt
Sent: Thursday, July 28, 2016 12:22 PM
To: address@hidden
Subject: Re: [lwip-users] Problems with sending UDP packets in FreeRTOS

Noam Weissman wrote:
> The reason is that if you send data to a wrong IP or domain and TCP 
> stack does not have the destination MAC address so it will issue ARP 
> messages. What if the ARP message fails ?... The TCP stack does not 
> know where to send the UDP packets. As a result if you continue to 
> send UDP packets they are added to the waiting packets to be sent. They are 
> never sent, memory is not freed and eventually you are without memory !!

This is *not* true for lwIP. Pending (unresolved) ARP entries get removed after 
5 seconds.
Queued packets will be freed on removal. If this shouldn't work, please file a 
bug!


Simon

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