Chapter 3 Authentication for FortiOS 5.0 : Agent-based FSSO : Agent installation
  
Agent installation
After reading the appropriate sections of “Introduction to agent-based FSSO” to determine which FSSO agents you need, you can proceed to perform the necessary installations.
Ensure you have administrative rights on the servers where you are installing FSSO agents. It is best practice to install FSSO agents using the built-in local administrator account. Optionally, you can install FSSO without an admin account. See “Installing FSSO without using an administrator account”.
 
In Windows 2008 by default, you do not have administrative user rights if you are logged on as a user other than as the built-in administrator, even if you were added to the local Administrators group on the computer.
The FSSO installer first installs the Collector agent. You can then continue with installation of the DC agent, or you can install it later by going to Start > Programs > Fortinet > Fortinet Single Sign On Agent > Install DC Agent. The installer will install a DC agent on the domain controllers of all of the trusted domains in your network.
 
Each domain controller connection needs a minimum guaranteed 64kpbs bandwidth to ensure proper FSSO functionality.Traffic shapers configured on the FortiGate can help guarantee these minimum bandwidths.