Virtual switch labels begin with a number.

Virtual switches within the ESX Server require a field for the name of the switch. This label is important since it serves as a functional descriptor for the switch. The labels of the virtual switches will not contain a number as the first character, since there have been known issues in the past that have caused erratic behavior. This has been especially true when renaming or removing the virtual switch. Labeling virtual switches will indicate the function or the IP subnet of the virtual switch. For instance, labeling the virtual switch as "internal" or some variation will indicate that the switch is only for internal networking between virtual machines private virtual switch with no physical network adapters bound to it.