You observe cyclic redundancy check (CRC) errors on a network port from a node in...

CRC errors on a network port usually indicate a physical-layer problem, so the first components to reseat or replace are the SFP and the cable. CRC errors are frame-check failures caused by corrupted frames reaching the interface. The most common support causes are dirty or failing optics, marginal fiber/copper cabling, bad seating, bend radius problems, or a faulty physical link component. Before replacing the controller port, the engineer should eliminate the replaceable path components that are cheaper, more common, and easier to validate. Cluster interconnect switches or upstream switches may eventually be involved if errors persist on multiple links or follow a switch port, but the question asks what to consider before taking action on the physical port where errors are reported from the node. Therefore, reseating or replacing the SFP and cable is the correct initial response. References/topics: ONTAP network port CRC errors, physical-layer troubleshooting, SFP optics, cabling validation, and network link diagnostics.