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Upon further investigation, we saw symptoms that was quite familiar to us. Layer 1 was working, as the LACP links was established, but there was no communication further up in the networking stack. We have seen this behavior before, and it is caused by a rare, known bug in openvswitch. This has been fixed in later versions of openswtich, and we had simply forgotten to upgrade to the packages on these three nodes the last time they were reinstalled.
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