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I have a FreeBSD (10) host connected to a Linux (Debian 7) box directly with a Cat 6 cable.

Both hosts have Intel X-540 10GBe NICs (ixbge).

Whenever there is heavy traffic (high PPS) from the FreeBSD side, the Link state between the adapters go down. Setting FC (Autoneg, RX/TX, all) off seems to not have any effect on this.

Neither OS kernels log anything useful, only message is about <interface>: NIC Link is Down After a half a second or so, the links goes back up.

  1. What might be the cause? or,
  2. how to troubleshoot this?


Tested with packet generator: It seems that it is exactly 8188 packets that get through and 8189th causes the link go down, regardless of packet size

EDIT 2: This seems to be the transmitting end (FreeBSD) that is to blame, connecting the port in question to another port on the same host yields the exact same results.

share|improve this question
Is the number of packets to trigger the problem the same regardless of packet rate? Or can you send more packets before the problem happens, if you send them at a lower rate? – kasperd Aug 11 '14 at 8:27
Requires a hot packet rate, and 8188 seems oddly close to 8192... Might be that there are 4 unrelated packets every time... – Kimvais Aug 11 '14 at 9:10
I had also such hard times with beelding-edge things on freebsd. A little kernel recompilation handled this problem. – peterh Aug 11 '14 at 10:07
Whenever this happens, grab following o/p on FreeBSD box and paste or link them: 0) uname -a 1) netstat -m 2) vmstat -z 3) sysctl -a (this one would be huge, pastebin it) – hari Aug 11 '14 at 22:50
It'd also be useful to see 1,2 and 3 before the problem and after the problem. – hari Aug 11 '14 at 22:53

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