What is virtualisation?

01 January 2009 |


Traditionally virtualisation describes the techniques of hiding the physical characteristics of computing resources from the way in which other systems, applications and users interact with them.

The term is widely used in computing, predominately in relation to the virtualisation of server capacity in data centres. Via the partitioning of servers, capacity has been maximised, cutting costs for large organisations and opening up the potential for smaller organisations to avoid the cost of an entire server when their requirements total far less than the total capacity. Virtual private networks (VPNs) are partitioned telecommunications connections enabling enterprises to avoid expensive dedicated circuits.

There are now additional types of virtualisation that have effects on telecoms networks. Virtualisation technologies such as server, storage and application virtualisation all have an impact on hardware, software and infrastructure requirements, but network virtualisation also has significant impact on service providers. Network virtualisation is, in essence, a means by which network resources can be combined by dividing available bandwidth into channels, each of which is independent and can be assigned to a specific server or device as required. Network virtualisation is the process of combining hardware and software network resources and functionality into a single, software-based virtual network. It can be categorised as external or internal virtualisation and, to complicate matters further, can also involve a combination internal and external network virtualisation.

How do external and internal network virtualisation differ?

External network virtualisation involves combining many networks or parts of networks into a virtual, single network to improve the efficiency of large networks or data centres. The key components of an external virtual network are the VLAN (virtual local area network) and the network switch itself. VLAN and switch technology allow the system administrator to configure systems that are physically attached to the same local network into different virtual networks. VLAN technology also enables the system administrator to combine systems on separate local networks into a VLAN that spans the segments of a large network. Examples of external network virtualisation include Cisco’s Service-Oriented Architecture or Hewlett-Packard’s X Blade Virtualization.

Internal network virtualisation provides network-like functionality whereby a single system is configured to isolate applications into separate “containers” or interfaces. This results in improved overall efficiency of the single system.

Benefits of network virtualisation

The technology is intended to remove much of the need for tedious, human administration of network management. Automation of many such tasks improves productivity and efficiency by disguising the true complexity of the network. In addition, it is intended to optimise network speed, reliability, flexibility, scalability and security. The technology is reportedly especially effective in networks that experience sudden, large and unforeseen usage surges.

General benefits of virtualisation

Virtualisation offers benefits in terms of business continuity, business agility, reduced downtime, test and development agility, server consolidation and security. Other advantages can include: enhanced capability to achieve service levels, better business reaction to staff mobility and location issues, reduced administration costs, support for legacy systems on new hardware without major upgrades, simplified deployment of complex applications and reduced floor space costs.

What are the challenges?

It’s all very well for corporations to institute virtualisation strategies across their LANs, but network providers are warning that such strategies could be doomed to failure if implementation is attempted over legacy core network architecture. Exponential-e has warned that, although companies are able to achieve great advances in business agility by pooling and sharing resources through virtualisation, they are not necessarily considering core connectivity as integral to their strategy. For instance, the company claims that often wide-area networks which glue geographically remote sites together and bring supplier and partner organisations into a single supply chain, are unable to support the full set of benefits that are possible through virtualisation.

Virtualisation has several other downsides. Cost accounting and licensing becomes more difficult in a virtual environment, existing management and monitoring tools may be problematic to use, increased uptime requirements may be hard to meet with existing hardware and issues such as unexpected additional costs for hardware and software may arise in addition to the bandwidth issue.

Are there any telecom-specific virtualisation innovations emerging?

Yes. Vendor Infinera has been marketing its Bandwidth Virtualization proprietary architecture that is claimed to transform the responsiveness of an optical network by decoupling the underlying physics of the optical layer from the practical need to deliver capacity between two or more locations. The technology is in use at several carriers, reportedly Level 3 and XO Communications to name a few. However, although the benefits are acknowledged, analysts claim the technology is only viable for very large bandwidth providers at present.