Multiple cells should be used to address availability and scalability. The is achieved by a load balancer or content switching front end layer. Load Balancer present a consistence address for the services regardless of the underlying node responding . They can be spread session load across cells and have monitoring cell health by add/remove cell from the active service pool.
Vcloud Director installation includes multiple cloud cells running behind a load balancer or NAT or if the cloud doe not have publicly routing IP address. It can be set to a public console proxy address.
Load Balancer that supports SSL, session persistence and has network connectivity to the public facing internet or internal service network can perform load balancing of Vcloud Director Cells as be consisted for security and manageability requirements.