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Lwip delayed ack problem with demo example

nic
Associate
Posted on December 30, 2013 at 15:45

Hi,

I am using STM3220-G Eval board.

Sample application ST library - \STM32F2x7_ETH_LwIP_V1.1.0\Project\FreeRTOS UDP_TCP_Echo_server-netconn.

No any changes to the examples. No any changes to the board.

To test this app. I send with a maximal speed packets with length from 60 to 1460 bytes.

At the beginning it works perfect. But after while (hundreds thousands of packets) I see the speed is reduced. With ethernet scan I can see that STM32 have delayed TCP Ack for few seconds. As a result computer send TCP retransmition telegrams. And STM32 sends Dublicate TCP Ack.

As soon as Evaluation board got this state. It reacts the same way for any also single TCP telegram from computer. The Disconnection and reconnection once more do not solve the problem. I have to restart Evaluation board to reset this behavior.

TO reduce the problem source i have tested it in a direct connection (no any switcher).

I set on debug mode on Lwip - I didn't get any warning messages no fault messages. I can see all the telegrams comes to and from Lwip stack with a correct CRC. 

I tried to switch off the Nagle Algoritm - but it had no effect.

I will appreciate any help about.

Thank you.

#lwip-stm32
1 REPLY 1
francescatodiego
Associate II
Posted on December 31, 2013 at 11:34

Unfortunately

I'm not using

lwip

You may

copy a

small

seqeunce

of

TCP messages

on the next

response

If I

remember correctly

after a delay

ACK

message 

TCP

flow should continue

normally, but

you say that the

PC

re-send a

message

previously

sent

and

correctly

STM32

sends

duplicate ACK

check the numbers

SEQ

/ ACK

field

s

for messages