I have encountered blocker while developing software for our client based on Apalis iMX6D Module. When sending huge files ( >1.1GB) through scp from Ixora Development Board to host PC with 100Mbit ethernet card the transfer is terribly slow or even stalled. Transfers in opposite direction (from Host PC to Apalis Module) works fine with constant 12MB/s rate. When we set up the host card to 1Gbit or 10Mbits the same configuration works well. We have verified our host PC connection with different 100Mbit ethernet device to prove that our testing set-up is correct.
When transmitted packets are small like for example in SSH connection the problem is not disturbing normal work but TCP retransmissions can be encountered as well.
Wireshark show multiple TCP retransmissions when sending huge file:
Some information about setup:
- Apalis iMX6D V.1.1A 512MB and V1.1B 1GB
- Beseboard: Ixora V1.0A or our custom baseboard with Micrel KSZ8895 (100Mbit) switch
- Linux apalis-imx6 4.9.67-+g1db9f06709ad #1 SMP Sat Feb 3 16:19:58 CET 2018 armv7l GNU/Linux
- Image built with Yocto, cloned from Index of /toradex-bsp-platform.git -b LinuxImageV2.8
- Image recipe: console-tdx-image.bb
- Host PC Ethernet Card: Intel® 82577LC Gigabit Ethernet PHY (100Mbit speed set up from userspace)
- Tested also with: KSZ8895 (100mbit switch)
We need to fix this issue because our baseboard is equipped with KSZ8895 (100Mbit) switch. Temporarily we decreased Ethernet Speed to 10Mbit for development but for our target system it’s not enough.
Have someone encountered similar issues? Any help will be appreciated.