Information
http://kb.vmware.com/kb/1022312
Solution
1. Connect to the vCenter Server using the Web Client.
2. Open the settings for Networking > (vDS name) > (dvPortgroup name) > Manage >
Edit Settings > General
3. Configure 'Port allocation' to 'Fixed'.
4. Configure the 'Number of Ports' to the exact amount required for legitimate virtual
machine connections to that dvPortgroup.
Default Value-The default state is the prescribed state.