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Symptoms: Link Flaps - Bad Optic

  • Server stor-node-05 has intermittent network connectivity on its 10G SFP+ interface (eth2).
  • Monitoring shows the link going down and up every 3-8 minutes.
  • During link-down events, storage replication traffic fails, causing replication lag alerts.
  • The server connects to a Cisco Nexus 9000 switch via a 10G DAC (Direct Attach Copper) cable.
  • The cable was replaced 2 weeks ago after a rack re-cabling project.
  • Other servers on the same switch and same VLAN are not affected.
  • The issue started approximately 3 days ago and has been gradually worsening.
  • dmesg on the server shows repeated "link is down" / "link is up" messages.
  • No configuration changes have been made to the server or switch port.