The term cloud refers to the internet-A network of Servers.Cloud is a buzzword that suggests the promise and convenience of being able to access files from anywhere.The Cloud Computing revolution is hitting full gear,and it is fueled by small to medium size company's. This book is written accordingly to the latest Riverbed Modeller and suggests the work on cloud simulation under different firewall conditions. Cloud Computing is the use of hardware and software to deliver a service over a network (typically the Internet). With cloud computing, users can access files and use applications from any device that can access the Internet.