A Linked Mode group allows you to log in to any single instance of vCenter Server and view and manage the inventories of all the vCenter Server systems in the group.
You can join multiple vCenter Server systems to form a Linked Mode group. You can configure a Linked Mode group during vCenter Server installation or after vCenter Server is installed.
To join a vCenter Server group, you enter the fully qualified domain name (or IP address) of a remote machine on which vCenter Server is running. The remote machine can be any vCenter Server instance that is, or will become, a member of the Linked Mode group.
You must also provide the LDAP port number of the remote vCenter Server instance.
vCenter Server instances in a group replicate shared global data to the LDAP directory. The global data includes the following information for each vCenter Server instance:
Connection information (IP and ports)
The vSphere Web Client can connect to a Linked Mode vCenter Server environment only if the vSphere Web Client is logged in to vCenter Server as a domain user. For example, if the Linked Mode vCenter Servers are installed with user "abc" added to domain "xyz," the vSphere Web Client user should log in using xyz\abc.
vCenter Server 5.1 can be joined in a Linked Mode group only with other instances of vCenter Server 5.1. Do not join a version 5.1 vCenter Server instance to a version 5.0 or earlier vCenter Server instance.