A UEC system includes physical machines running the following services:

 1. '''eucalyptus-cloud''' - includes the front-end services, Cloud Controller
 1. '''eucalyptus-cc''' - includes the Cluster Controller that provides support for the virtual network overlay
 1. '''eucalyptus-sc''' - includes the Storage Controller
 1. '''eucalyptus-walrus''' - includes the Walrus storage system
 1. '''eucalyptus-nc''' - includes the Node Controller that interacts with [[KVM]] through Libvirt to manage individual VMs

In a basic UEC setup, the system is composed of two machines (a front-end and a node).  The front end runs both `eucalyptus-cloud` and `eucalyptus-cc` in this configuration.  The node runs the node controller, `eucalyptus-nc`.  It is possible to separate the cloud controller and cluster controller in a more complex multi-host setup.
The following diagram depicts a simple setup:

{{attachment:UEC/Architecture/euca-topo-nonet.png}}

UEC assumes that each node in the system belongs to a cluster and that each cluster belongs to a cloud.  Each node runs the eucalyptus-nc service.  Similarly, each cluster (again, there is only one cluster in this example) must run the eucalytpus-cc service.  These components must be registered with each other before the system starts.