Objective 9.5 – Troubleshoot Common vSphere Networking Issues

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Knowledge

This is the same as VCP5-DCV exam blueprint section 6.2

  • Verify network configuration
    • Use host profiles where possible to ensure consistent configuration
    • Use vDS where possible to minimise configuration effort across multiple hosts
    • Check configuration of Port Groups / dvPort Groups
    • Check Load Balancing and Failover Policies
    • Check Security Policies (Promiscuous Mode, Forged Transmits etc)
    • Verify that VLAN settings are correct and consistent across a cluster
  • Verify a given virtual machine is configured with the correct network resources. KB1003893 is a good resource for this but as a start:
    • Check that the network associated with the VM’s vNIC exists, and the spelling is consistent across the infrastructure.
    • Check that the “connected” checkbox for the vNIC is checked.
    • Ensure the networking is configured correctly within the Guest OS
    • Verify that the vSwitch has sufficient ports to support the VM
    • Check the uplinks for the vSwitch are consistent (same VLANS)
  • Troubleshoot virtual switch and port group configuration issues
    • Correct spelling of port group names is important and is case sensitive. Consistency of naming and Security Configuration is vital for the smooth running of the infrastructure.
    • Ensure switches are configured correctly (as per point 1) and with sufficient available ports.
  • Troubleshoot physical network adapter configuration issues
    • Ensure all physical NICs assigned to a vSwitch are configured with the same speed, duplex and VLANs on the physical switch
    • If using IP Hash as the load balancing method, ensure Link Aggregation is configured on the switch.
    • You can use CDP or LLDP to assist with network troubleshooting, it will identify the switch ports that are connected to each pNIC.
  • Identify the root cause of a network issue based on troubleshooting information
    • The root cause is likely to fall into one of 4 main areas:
      • VM
      • Port Group / vSwitch configuration
      • Host Uplinks
      • Physical Switch configuration
    • Use the above notes to assist with determining the area at fault – working from the VM down is probably easiest.
    • vmkping –D can be used to ping out through vmknics

Tools

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