Assuming IPv6 hasn't been rolled out yet in your environments, are you leaving IPv6 on or off on your ESXi servers and vCenter?
Logic would suggest turning it off would be sensible, but quite honestly I've not noticed any impact either way, and there's even some bug reports / KBs out there re: PSODs if you *do* disable.
Interested to know what you all do.
Vmware has not made a clear decision towards IPv6, however I advise you if it is not necessary to leave it enabled (default).
Other vendors advise not to disable it in order not to compromise the stability of their operating system (eg Microsoft).
This is an example of why IPv6 should not be disabled