Re: [lwip-users] Duplicate ACK issue lwIP 1.4.0

[Enrico Murador - Research & Development - CET]

...and if it could help (and if I'm not wrong) that packet was correctly retransmitted (packet 188), so maybe packet 167 has effectively been altered after creation.

On 09/11/2015 10:29, Enrico Murador - Research & Development - CET wrote:

Hi,
I gave only a quick look at the log... I stopped at packet 167, that is a malformed part of a TCP ECHO response sent by Xilinx board. This message has some fields not OK: Ethernet frame type, IP version field, and an IP service field. All of these are located in a 32bit word starting at 0x0C from start of message, so you have an 0x40000000 instead of 0x08004500 at that location.

I could say there are some problems with multithreading and/or with your ethernet low level driver, but you probably already checked these parts. Maybe some other function in your system is "simply" writing a longword in memory at the wrong place?
Don't know if this issue could be related with duplicate ACKs (surely it is related with the "TCP previous segment not captured" at packet 168), but I would try to resolve it first.

Enrico

On 06/11/2015 10:16, address@hidden wrote:

Hi,

 

My system is on a Xilinx Microblaze.  I am running lwIP 1.4.0 under FreeRTOS.  I am using it in raw mode with a single tcpip thread.

 

I have an issue where I am getting duplicate ACKs and the connection is failing.  I am not sure what exactly is the cause but Wireshark (attached) shows duplicate ACKs.  lwIP is on port 7 @ 192.168.1.10.

 

I have tried different settings and get minor changes.  This occurs during a high traffic loading sequence.

 

I have set the lwIP task at the highest priority and it loads 95% of the time but still occasionally gets the issue.  However I don't wish it to be the highest priority as there are more important (but with low computational effort) tasks.  When I lower it to a mid priority task it loads maybe 5% of the time.

 

I have DDR memory in the system and have a large heap and have allocated a lot of pbuf memory.

 

Anyone have any ideas on what might be causing my issue and suggestions on how to fix/improve it?

 

Thanks,

 

Tim

 

 

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Enrico Murador
R&D

CET Electronics snc via E. Fermi, 1 31050 Zenson di Piave (TV) Italy Phone: +39 0421 344100 Fax: +39 0421 464042 PI/VAT IT01780330260 Web: http://www.cet-electronics.com/