Reordering caused by Flow Director

[JAuer1]

Hi,

we are experiencing packet reordering and thus bandwidth drops due to retransmissions on our servers. We are using RedHat 7.2 on HP Servers connected to a HP Aruba 1920 10GB switch. I can easily reproduce the issues by running iperf3 between the two servers. I have found a description of problems caused by Flow Director and migrating processes from Fermilab (https://mail.logica.com/owa/redir.aspx?C=VmeSIGgGxU6ljzLEwM20iBNG41y90NMIwuS9-EdO6GyiwXDZdcHLDijsUbTEgCDTWTNDRNZQGpI.&URL=https://arxiv.org/pdf/1106.0443.pdf https://arxiv.org/pdf/1106.0443.pdf) together with a support case at RedHat (https://mail.logica.com/owa/redir.aspx?C=VmeSIGgGxU6ljzLEwM20iBNG41y90NMIwuS9-EdO6GyiwXDZdcHLDijsUbTEgCDTWTNDRNZQGpI.&URL=https://access.redhat.com/solutions/2403071 https://access.redhat.com/solutions/2403071). What is offical position concerning this issue? Is it considered as bug?

An iperf test shows the retransmissions every couple of seconds:

iperf3 -c 192.168.120.11 -p 12345 -b200m -P20 -t0 Connecting to host 192.168.120.11, port 12345 [ 4] local 192.168.120.10 port 59638 connected to 192.168.120.11 port 12345 [ 6] local 192.168.120.10 port 59640 connected to 192.168.120.11 port 12345 [ 8] local 192.168.120.10 port 59642 connected to 192.168.120.11 port 12345 [ 10] local 192.168.120.10 port 59644 connected to 192.168.120.11 port 12345 [ 12] local 192.168.120.10 port 59646 connected to 192.168.120.11 port 12345 [ 14] local 192.168.120.10 port 59648 connected to 192.168.120.11 port 12345 [ 16] local 192.168.120.10 port 59650 connected to 192.168.120.11 port 12345 [ 18] local 192.168.120.10 port 59652 connected to 192.168.120.11 port 12345 [ 20] local 192.168.120.10 port 59654 connected to 192.168.120.11 port 12345 [ 22] local 192.168.120.10 port 59656 connected to 192.168.120.11 port 12345 [ 24] local 192.168.120.10 port 59658 connected to 192.168.120.11 port 12345 [ 26] local 192.168.120.10 port 59660 connected to 192.168.120.11 port 12345 [ 28] local 192.168.120.10 port 59662 connected to 192.168.120.11 port 12345 [ 30] local 192.168.120.10 port 59664 connected to 192.168.120.11 port 12345 [ 32] local 192.168.120.10 port 59666 connected to 192.168.120.11 port 12345 [ 34] local 192.168.120.10 port 59668 connected to 192.168.120.11 port 12345 [ 36] local 192.168.120.10 port 59670 connected to 192.168.120.11 port 12345 [ 38] local 192.168.120.10 port 59672 connected to 192.168.120.11 port 12345 [ 40] local 192.168.120.10 port 59674 connected to 192.168.120.11 port 12345 [ 42] local 192.168.120.10 port 59676 connected to 192.168.120.11 port 12345 [ ID] Interval Transfer Bandwidth Retr Cwnd [ 4] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 2 225 KBytes [ 6] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 1 202 KBytes [ 8] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 8 225 KBytes [ 10] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 2 132 KBytes [ 12] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 2 133 KBytes [ 14] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 2 132 KBytes [ 16] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 12 165 KBytes [ 18] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 2 151 KBytes [ 20] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 1 150 KBytes [ 22] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 4 225 KBytes [ 24] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 5 143 KBytes [ 26] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 3 132 KBytes [ 28] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 3 126 KBytes [ 30] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 1 127 KBytes [ 32] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 6 136 KBytes [ 34] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 2 139 KBytes [ 36] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 1 154 KBytes [ 38] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 1 136 KBytes [ 40] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 2 122 KBytes [ 42] 0.00-1.00 sec 21.9 MBytes 183 Mbits/sec 4 139 KBytes [SUM] 0.00-1.00 sec 438 MBytes 3.67 Gbits/sec 64 - - - - - - - - - - - - - - - - - - - - - - - - - [ 4] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 255 KBytes [ 6] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 243 KBytes [ 8] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 256 KBytes [ 10] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 191 KBytes [ 12] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 192 KBytes [ 14] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 192 KBytes [ 16] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 216 KBytes [ 18] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 208 KBytes [ 20] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 205 KBytes [ 22] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 259 KBytes [ 24] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 202 KBytes [ 26] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 198 KBytes [ 28] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 191 KBytes [ 30] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 192 KBytes [ 32] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 201 KBytes [ 34] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 198 KBytes [ 36] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 211 KBytes [ 38] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 198 KBytes [ 40] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 194 KBytes [ 42] 1.00-2.00 sec 24.0 MBytes 201 Mbits/sec 0 198 KBytes [SUM] 1.00-2.00 sec 480 MBytes 4.03 Gbits/sec 0 - - - - - - - - - - - - - - - - - - - - - - - - - [ 4] 2.00-3.00 sec 23.8 MBytes 199 Mbits/sec 0 267 KBytes [ 6] 2.00-3.00 sec 23.8 MBytes 199 Mbits/sec 0 250 KBytes [ 8] 2....