We will be using 3 virtual machines as 3 Ethereum node. We used 'Ubuntu Server 14.04 LTS trusty', and 'Ubuntu 15.10 wily' for this experiment. Root Ethereum node will be referred as 'root node', client nodes will be referred as 'client node A' & 'client node B' respectively. On root node port 30303 must be accessible from outside.
Below are the installation instructions for the latest versions of Ubuntu. This step must be executed and Ethereum go client 'geth' must be installed on every node.