Upgrading to VMware vCenter Server 5.1 Best Practices w/ Video
vCenter Single Sign On
vSphere 5.1 introduces the vCenter Single Sign On service as part of the vCenter Server management infrastructure. This change affects vCenter Server installation, upgrading, and operation.
Authentication by vCenter Single Sign On makes the VMware cloud infrastructure platform more secure by allowing the vSphere software components to communicate with each other through a secure token exchange mechanism, instead of requiring each component to authenticate a user separately with a directory service like Active Directory.
To learn more and to read the entire article at its source, please refer to the following page, Upgrading to vCenter Server 5.1 best practices (2021193)- VMware Knowledge Base – latest articles