If you have a support contract with Vmware there’s a few upgrade routes you can take without purchasing licenses per link : http://kb.vmware.com/kb/2059926
4.x> 5.0,5.1,5.5
5.1 -> 5.5
5.5 -> 6
If you have a support contract with Vmware there’s a few upgrade routes you can take without purchasing licenses per link : http://kb.vmware.com/kb/2059926
4.x> 5.0,5.1,5.5
5.1 -> 5.5
5.5 -> 6