Network virtualization is best defined as . . .

When technology vendors say they offer network virtualization, what do they mean? The answer isn’t as straightforward as it might seem. Ask around, and you’ll find some people saying network virtualization specifies VLANs. Others insist VLAN functionality is merely an aspect of virtualization.

Researchers at North Carolina State University (NCSU) have attempted to tackle the matter. In a report titled Network Virtualization, Technologies, Perspectives and Frontiers, they discuss their analysis of various concepts and definitions, looking for common characteristics to inform an all-encompassing definition.

This is a noteworthy exercise, made all the more so considering the researchers’ concluding definition:

“Network virtualization is any form of partitioning or combining a set of network resources, and presenting (abstracting) it to users such that each user, through its set of the partitioned or combined resources has a unique, separate view of the network. Resources can be fundamental (nodes, links) or derived (topologies), and can be virtualized recursively. Node and link virtualization involve resource partition/combination/abstraction; and topology virtualization involves new address spaces.”

Although the definition is far from succinct, it’s entirely sensible: the researchers effectively say network virtualization lets administrators divide or combine network resources, present these resources such that users see them in different ways, and repeat the virtualization process relatively easily.

How do real-world network virtualization systems compare with the NCSU definition? Consider Avaya’s and Cisco’s descriptions of the technology. They indicate that the market may be zeroing in on a reasonable compromise.

Avaya uses virtualization in its Virtual Enterprise Network Architecture. VENA employs shortest path bridging to form a multipath Ethernet network that dynamically creates a topology between nodes. The solution requires service provisioning only at the network edge, not in the core.

This approach means administrators can deploy new services quickly, says Jean Turgeon, Avaya Canada’s VP for technical solutions. “Now you don’t have to touch every hop along the way. The network finds the path dynamically.” The process also reduces the chances of misconfigurations in virtual network set-up.

Cisco’s idea of virtualization is similar, reinforcing the idea that the industry may yet attain consensus. This company’s definition indicates that the technology enables network resources to be deployed and managed as services, rather than physical resources. That means administrators can consolidate numerous physical networks into a single virtual network. Network managers can also divide a single physical network into multiple networks for different loads, applications and end-user groups.

Jeff Seifert, Cisco Canada’s CTO, explains that network virtualization is making its way from the carrier realm to the enterprise level.

“Private- and public-sector customers are now rapidly adopting network virtualization as a way of turning up new services and applications quickly and securely,” he says.

Seifert adds that the trend to connect more devices and systems to a network drives business interest in network virtualization. “Networking has extended well past the connection of desktop computers to include connecting point-of-sales systems, building-management systems, security badge readers and video surveillance cameras. Network virtualization removes the time and cost associated with building separate physical networks for each.”

The similarities between NCSU’s definition—and those of Avaya and Cisco—suggest the fog may be lifting on our understanding of network virtualization.