In recent years, network virtualisation has been of great interest to researchers, being a relatively new and major paradigm in networking. This has been reflected in the IT industry where many virtualisation solutions are being marketed as revolutionary and purchased by enterprises to exploit these promised performances. Nevertheless, challenges such as trust, security and complete isolation remain to be tackled. In this study, an investigation of the different state-of-the-art virtualisation technologies, their issues and challenges are addressed. A systematic review was effectuated on selectively picked research papers and technical reports. Moreover, a comparative study has been performed on different network virtualisation technologies which include features like security, isolation, stability, convergence, outlay, scalability, robustness, manageability, resource management, programmability, flexibility, heterogeneity, legacy support, and ease of deployment. The virtualisation technologies comprise Virtual Private Network (VPN), Virtual Local Area Network (VLAN), Virtual Extensible Local Area Network (VXLAN), Software Defined Networking (SDN) and Network Function Virtualisation (NFV). Conclusively results exhibits that these technologies overlooked some features to promote other features. Moreover, further discussion exhibits the need for an improvement of the existing network virtualisation environment by exploring the vital drawbacks.