For an improved performance in the delivery of virtual desktop applications, you can integrate the NetScaler appliance with Citrix XenDesktop and use the NetScaler load balancing feature to distribute the load across the Web Interface servers and the Desktop Delivery Controller (DDC) servers.
Generally, you use XenDesktop in situations where applications are not compatible with running on a terminal server or XenApp, or if each virtual desktop has unique requirements. In such cases, you need one desktop host for each user that connects. However, the hosts can be pooled so that you need only one host for each currently connected user.
The core application service deployed for XenDesktop is the Desktop Delivery Controller (DDC). The DDC is installed on a server, and its main function is to register desktop hosts and broker client connections to them.
The DDC also authenticates users and manages the assembly of the users' virtual desktop environments by controlling the state of the desktops, and starting and stopping the desktops.
Generally, multiple DDCs are installed to enhance availability.
The Web Interface servers provide secure access to virtual desktops. The Web Interface is the initial connection portal to the Desktop Delivery Controller (DDC). The Web browser on the user's device sends information to the Web server, which communicates with the server farm to provide the user with access to the virtual desktop.
The following figure shows the topology of a NetScaler appliance working with XenDesktop.
Figure 1. Load Balancing of XenDesktop