Been getting the message below recently. Opened a ticket with Netapp support when we've seen this some months ago, and after a long investigation, their conclusion was that the message is informational. However, now this is showing up on a different filer (FAS 8200 running CDOT 9.1). We have iscsi boot LUNs, as well as normal iscsi LUNs being accessed from VMs.
Description: This event is issued when an initiator violates the iSCSI protocol.
Corrective Action: Attempt to configure the initiator such that the protocol violation does not occur. If the event occurs occasionally but does not affect stability or performance, no corrective action is needed but the event should be monitored. If the event persists and/or iSCSI application performance degrades, starting and stopping the iSCSI service and restarting any iSCSI applications may help clear the condition. Contact NetApp technical support.