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From: | Adrian Figueroa |
Subject: | [lwip-users] TCP Dup ACKs and TCP Window full |
Date: | Tue, 10 Apr 2018 14:53:31 +0000 |
I took some steps to see if the packet loss problem can be solved: - Migrated to ChibiOS 18.2 with Lwip 2.0.3 - Used only internal ram of STM32 instead of SDRAM Firstly, jumping to Lwip 2.0.3 made no difference at all. I think, this problem is not caused by Lwip itself but probably a configuration error or some buffer that runs full. Maybe even a speed issue of the processor. However, when using internal ram of STM32, the packet losses are much decreased. I know SDRAM works slower than internal ram, but why would this be a problem? I see that the TCP window gets fuller and fuller, as the host PC sends data quicker than the processor can evaluate. Even when no packets are dropped, I still get lots of TCP window full messages. Here you find a complete transmission without errors, and one transmission with some errors (lost packet at frame 73). I had to upload them here, because they were rejected as an attachment due to size. (no errors) https://packettotal.com/app/analysis?id=be214249b9478b1be3763a0f81e70312 (with errors) https://packettotal.com/app/analysis?id=4bdc7a415da7708b95df2c2a637795fc In both cases, internal ram is used on the STM32. Please filter with: tcp.port==44000 Do you have some suggestions, how to improve the Lwip configuration settings? I attach them to this mail. This is a new version of configuration settings, adjusted to Lwip 2.0.3. Now, only those values are included that differ from the default settings. Thanks in advance, Adrian Von: lwip-users <address@hidden> Im Auftrag von Adrian Figueroa Yes, I noticed but did not know what to make of it. I now disabled this offloading feature and have a new capture, attached to this mail. 192.168.0.101 is my host PC, 192.168.0.100 is the STM32. The first Dup Ack happens at frame 40. I am not sure why the TCP window is full at some point. Is the processor too slow to clear the receive buffers? Best regards, Adrian Von: lwip-users <address@hidden> Im Auftrag von address@hidden On 06.04.2018 15:30, Adrian Figueroa wrote:
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