The following are the issues encountered when NetScaler VPX is run on VMware ESXi 5.1.0 2191751, VMware ESXi 5.5 2143827 and also on VMware ESXi 6.0 

• Network disconnectivity.

• NetScaler GUI access is affected.

• When running show interfaces command from NetScaler CLI you might notice that one of the interfaces has stalls and errors.

To fix this issue upgrade to NetScaler 10.5 build 55.8. This firmware can be download from Citrix Downloads.

For more information, see Fixed Issues section from NetScaler 10.5 Build 55.8 Release Notes.

The following are the workarounds for this issue:

Workaround 1

Install NetScaler VPX appliance on a previously known good VMware version and build.

Workaround 2

1. SSH and log on to Citrix NetScaler VPX appliance as nsroot.

2. Type shell.

3. Change directory (cd) to /flash/boot.

4. Create file /flash/boot/loader.conf.local (if not present) with same permissions as /flash/boot/loader.conf. Add the following line and reboot:
   hw.em.txd=512
   Note: To create the file, use command touch loader.conf.local.

vi Commands

The following are the vi commands to edit the document:

1. From NetScaler shell type:
   vi <filename>

2. Move the cursor to the last character of text in the file, type "a" and click Enter.

3. Type the line:
   hw.em.txd=512

4. Press the ESC key and then ":" key. The cursor will move to the bottom of the page, then type wq!.

Problem Cause

NetScaler VPX network connectivity issue on VMware ESXi 5.1.0 build 2191751 and VMware ESXi 5.5 build 2143827 is caused by "tx_ring_length" mismatch, which causes TX stalls.

For more information refer to VMware Knowledge Base - 2092809.