"To understand the need for the Open vSwitch, you have to realize that while CPU virtualization, including hardware support, has evolved rapidly over the last decade, network virtualization has lagged behind pretty badly." This statement, and many more besides, occurs in a blog published Monday by Simon Crosby, CTO of the Datacenter and Cloud Division at Citrix.

"The dynamism that virtualization enables is the enemy of today's locked down enterprise networks," Crosby (pictured) adds.

In case there is anyone unclear as to the point of an open source virtual switch, Crosby stops up and offers the following overview at the beginning of his posting:

"The Open vSwitch is an open source virtual switch for Xen (and therefore XenServer, and in future perhaps Amazon EC2 and RackSpace), and KVM based virtual infrastructure that replaces the Linux bridge code with a powerful, programmable switch forwarding capability as well as programmable per-virtual interface ACLs."

With the Open vSwitch in place, Crosby explains, the Open Stack open source cloud orchestration layer will be able to exert direct control over the data center fabric to deliver a rich, enterprise ready network layer with powerful controls for security, multi-tenancy, load balancing, monitoring, compliance, charge-back and more.

Later in his blog post, Crosby gives a good account of the exciting potential of the Open vSwitch:

"The Open vSwitch, answers many of the shortcomings of our original hypervisor bridge code, which grew up from the Linux bridge code, and adds powerful features traditionally found only in dedicated switching infrastructure, such as packet filtering, flow admission control and programmable forwarding. It permits us to take advantage of the incredible price/performance benefits of packet processing on standard CPUs, and the near term addition of so-called Single Root I/O Virtualization (SR-IOV) to the edge packet processing feature set will enable the most profound changes in data center and cloud networking architecture since the invention of the router.

Most importantly, the Open vSwitch is open source, and will serve multiple hypervisors. I fully expect the community to make it available as a drop-in replacement for the VMware vDS, and to deliver versions of it for a future release of Hyper-V. This then raises the exciting prospect of an entirely open and programmable architecture for networking in the cloud, that is hypervisor independent."

As a result, Crosby reiterates, the richness of both private and public cloud networks (and hence their ability to support a greater proportion of enterprise workloads) will not be hypervisor dependent.

In Crosby's opïnion, Open vSwitch offers the ISV ecosystem an enormous opportunity to innovate in edge networking, free of the constraints of traditional network-appliance centric approaches to application delivery, with new, automated management and control plane functions that simplify, accelerate and ease the management of scalable cloud networks.

"The Open vSwitch is a reminder of the incredible power of open source," notes Crosby in conclusion.