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After applying patches to an ESXi 5.1/5.5/6.0 host, Citrix NetScaler virtual machine with e1000 vNIC loses network connectivity (2092809)

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After patching your ESXi host to version 5.5 Update 2 (build 2143827), 5.1 Patch 6 (build 2191751), 6.0 or a later build, you experience these symptoms:
  • Some Citrix NetScaler virtual machine appliance running the guest Operating System with e1000 vNIC driver loses network connectivity
  • Cannot access the console after applying the patches


This issue occurs when the NetScaler virtual machine driver resets TDT to 0 after 511 while the TX ring size is shown as 1024.


This is a known issue affecting Citrix NetScaler virtual machine appliances running on hosts running these builds of ESXi or later build: 5.5 Update 2 (build 2143827), ESXi 5.1 Patch 6 (build 2191751), or 6.0.

This is not a VMware issue. To resolve this issue, upgrade the NetScaler appliance.
Note: The preceding link was correct as of February 16, 2015. If you find the link is broken, provide a feedback and a VMware employee will update the link.
To work around this issue when you cannot upgrade, use one of these options:
  • Install NetScaler VPX appliance on a previously known good VMware version and build.
  • Add the line hw.em.txd=512 in the loader.conf.local file.

    To add the line hw.em.txd=512 in the loader.conf.local file:

    1. Log in to the Citrix NetScaler virtual machine appliance as root.
    2. Locate the loader.conf.local file on the NetScaler virtual machine appliance by running this command:

      find / -name loader.conf.local

      Note: The loader.conf.local file may not exist. If so, create this file under directory /flash/boot.

    3. Add this line in the loader.conf.local file.


    4. Save the changes.
    5. Restart the NetScaler virtual machine appliance. 


TX Stalls

See Also

Update History

11/12/2014 - Added ESXi 5.1 to Products

Request a Product Feature

To request a new product feature or to provide feedback on a VMware product, please visit the Request a Product Feature page.


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  • 34 Ratings