High packet rate ethernet with LwIP

On 2019-09-25 David Brown wrote in comp.arch.embedded:
> On 25/09/2019 06:55, upsidedown@downunder.com wrote:
>> On Tue, 24 Sep 2019 14:22:51 +0200, Stef
>> <stef33d@yahooI-N-V-A-L-I-D.com.invalid> wrote:
>> 
>>>
>>> What seems weird to me is that all ACK are followed by Dup ACK. Is this normal? See that al lot in other TCP traffic as well, but not on all ACK.
>>  
>> The difference between Ack and duplicate Ack is only 8-9 us. Strange.
>> 
>
> It is, I think, due to lost packets.  (Google "wireshark dup ack" for
> suggestions.)

Even stranger, when I just ping the board:

229	5.081046	192.168.125.128	192.168.125.133	ICMP	74	Echo (ping) request  id=0x0001, seq=3492/41997, ttl=128 (no response found!)
230	5.081051	192.168.125.128	192.168.125.133	ICMP	74	Echo (ping) request  id=0x0001, seq=3492/41997, ttl=128 (reply in 234)
234	5.081615	192.168.125.133	192.168.125.128	ICMP	74	Echo (ping) reply    id=0x0001, seq=3492/41997, ttl=255 (request in 230)

A duplicate request goes out from W10 with only 5 us difference? The same
happens on the rest of the pings, one second apart.

Nothing to do with the eval kit with LwIP, if I ping my router:

380	7.010693	192.168.125.128	192.168.125.254	ICMP	74	Echo (ping) request  id=0x0001, seq=3539/54029, ttl=128 (no response found!)380	7.010693	192.168.125.128	192.168.125.254	ICMP	74	Echo (ping) request  id=0x0001, seq=3539/54029, ttl=128 (no response found!)
381	7.010700	192.168.125.128	192.168.125.254	ICMP	74	Echo (ping) request  id=0x0001, seq=3539/54029, ttl=128 (reply in 382)
382	7.011670	192.168.125.254	192.168.125.128	ICMP	74	Echo (ping) reply    id=0x0001, seq=3539/54029, ttl=255 (request in 381)

And after looking a little better, it seems to happen on almost all
packets transmitted from this PC, but not on TLSv1.2 packets.

Something weird in W10 or Wireshark? Or the PC network interface?


-- 
Stef    (remove caps, dashes and .invalid from e-mail address to reply by mail)

Intolerance is the last defense of the insecure.