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Troubleshooting network connectivity with Virtual Switch Tagging (VST) / External Switch Tagging (EST) mode on an ESX/ESXi host (1008001)


You experience these symptoms on ESX/ESXi vSwitch port groups:

  • Service Console is unable to ping the gateway IP
  • Virtual machine fails to ping gateway
  • VMkernel networking issues
  • You receive one or more of the following errors:
    • Destination Host Unreachable
    • Ping request could not find host <IP address/hostname>.  Please check the name and try again.
    • Could not open connection to the host, on port ##: Connection failed


To troubleshoot network connectivity with Virtual Switch Tagging (VST) mode, you must check the VLAN configuration on ESX/ESXi.
To check VLAN configuration on ESX/ESXi: 

  1. Verify the Virtual Switch (vSwitch) VLAN ID. For more information, see Configuring a VLAN on a portgroup (1003825).

  2. For Virtual Switch Tagging (VST) ensure that VMNICs uplink to switch port is set to TRUNK MODE.

    For External Switch Tagging (EST) ensure that VMNICs uplink to switch port is set to ACCESS MODE.

    For more information, see Sample switch port configuration for VLAN and TRUNK MODE (1006628).

  3. Utilize Cisco Discovery Protocol (CDP) information to establish switch port configuration settings and correct port configuration accordingly. For more information, see Cisco Discovery Protocol (CDP) network information via command line and VirtualCenter on an ESX (1007069).

    To test this functionality, do a PING and TCPDUMP analysis of ICMP messages. For more information, see Troubleshooting gateway IP connectivity issues via TCPDUMP command (1008017).

  4. If EtherChannel and NIC teaming is configured, verify EtherChannel configuration. For more information, see Sample configuration using EtherChannel, ESX  and a Cisco switch (1004048).

  5. You can use the ESXi Network Dump Collector in ESXi 5.0 for collecting data and further troubleshooting.  For more information, see ESXi Network Dump Collector in VMware vSphere 5.x (1032051).

Additional Information

See Also

Update History

07/22/2010 - Added ESX 4.0 to Product Versions 06/18/2012 - Updated to include information about Network Dump Collector. Updated for 5.x. 07/26/2012 - Minor formatting changes.

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