Can be triggered when running 'iperf -c xxx.xxx.xxx.xxx' on this server and 'iperf -s' on another server.
Does not happen when running 'iperf -s' running on this server and 'iperf -c xxx.xxx.xxx.xxx' on another server.

In some occasions another error is kicking in too (Bad DLLP):

[  302.497045] pcieport 0000:00:1c.4: AER: Multiple Corrected error received: id=00e4
[  302.497068] pcieport 0000:00:1c.4: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=00e4(Receiver ID)
[  302.498022] pcieport 0000:00:1c.4:   device [8086:8c18] error status/mask=00000001/00002000 id=00e4(Receiver ID)
[  302.498493] pcieport 0000:00:1c.4:    [ 0] Receiver Error         (First)=00000001/00002000
[  302.498943] pcieport 0000:00:1c.4:   Error of this Agent(00e4) is reported first
[  302.499396] netxen_nic 0000:07:00.1: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0701(Receiver ID)
[  302.499865] netxen_nic 0000:07:00.1:   device [4040:0100] error status/mask=00002080/00002000d=00e4(Receiver ID)
[  302.500345] netxen_nic 0000:07:00.1:    [ 7] Bad DLLP              
[  302.500831] netxen_nic 0000:07:00.2: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0702(Receiver ID)
[  302.501281] netxen_nic 0000:07:00.2:   device [4040:0100] error status/mask=00002080/00002000
[  302.501764] netxen_nic 0000:07:00.2:    [ 7] Bad DLLP              ed, type=Physical Layer, id=00e4(Receiver ID)
[  302.502222] netxen_nic 0000:07:00.3: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0703(Receiver ID)
[  302.502689] netxen_nic 0000:07:00.3:   device [4040:0100] error status/mask=00002080/00002000
[  302.503133] netxen_nic 0000:07:00.3:    [ 7] Bad DLLP              
[  334.551474] pcieport 0000:00:1c.4: AER: Multiple Corrected error received: id=00e4
[  334.551502] pcieport 0000:00:1c.4: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=00e4(Receiver ID)
[  334.551980] pcieport 0000:00:1c.4:   device [8086:8c18] error status/mask=00000001/00002000
[  334.552436] pcieport 0000:00:1c.4:    [ 0] Receiver Error         (First)
[  469.354652] pcieport 0000:00:1c.4: AER: Corrected error received: id=00e4
[  469.354665] pcieport 0000:00:1c.4: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=00e4(Receiver ID)
[  469.355151] pcieport 0000:00:1c.4:   device [8086:8c18] error status/mask=00000001/00002000
[  469.355634] pcieport 0000:00:1c.4:    [ 0] Receiver Error         (First)
[  471.814493] pcieport 0000:00:1c.4: AER: Corrected error received: id=00e4
[  471.814506] pcieport 0000:00:1c.4: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=00e4(Receiver ID)
[  471.815003] pcieport 0000:00:1c.4:   device [8086:8c18] error status/mask=00000001/00002000
[  471.815498] pcieport 0000:00:1c.4:    [ 0] Receiver Error         (First)
[  472.548669] pcieport 0000:00:1c.4: AER: Corrected error received: id=00e4
[  472.548683] pcieport 0000:00:1c.4: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=00e4(Receiver ID)
[  472.549202] pcieport 0000:00:1c.4:   device [8086:8c18] error status/mask=00000001/00002000
[  472.549708] pcieport 0000:00:1c.4:    [ 0] Receiver Error         (First)
[  473.141720] pcieport 0000:00:1c.4: AER: Corrected error received: id=00e4
[  473.141728] pcieport 0000:00:1c.4: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=00e4(Receiver ID)
[  473.142254] pcieport 0000:00:1c.4:   device [8086:8c18] error status/mask=00000001/00002000
[  473.142772] pcieport 0000:00:1c.4:    [ 0] Receiver Error         (First)