Re: [lwip-users] Can't process incoming UDP packets afteroneofhosts is powered down

[Grzegorz Niemirowski]

I've finally found the answer.

Powering a computer down causes its MAC<->port entry to expire on my switch. 
SYN packets sent by my device to that computer start to be visible by my 
router. It responds with ICMP packets (type 5 code 1) which causes 
allocations in NETBUF pool by lwip. Simple pinging my device resulted in 
NETBUF saturation as well. Why? Because I had RAW ICMP socket open which I 
have completely forgotten about. It was used for pinging. Data from that 
socket were read only when pinging other hosts was needed, which was very 
rarely. This way NETBUF pool, used also for UDP, was not freed up and 
blocked UDP processing.

Thank you all who answered in this thread.

Best regards,
Grzegorz Niemirowski
http://www.grzegorz.net/