This is the first of a series of articles titled “The vIRTUAL Series” that will be talking about Software defined technologies, virtualization, cloud computing and Internet of things.

Software Networks: Network Virtualization(NV)

Network Virtualization(NV), Network Functions Virtualization(NFV) and Software Defined Networking(SDN) are no longer buzzwords in the field of IT, they are now technologies that will rapidly influence the way we administer and provision networks. This post takes a look at Network Virtualization and its benefits.

Often times, network administrators are faced with the burden of having to alter the configuration on a network device, be it a switch, firewall or a router whenever a new application comes on board. They are required to reconfigure Virtual LAN’s (VLANs), Access Control Lists (ACLs) and the likes. This usually takes quite some time to achieve and with time, it becomes monotonous.

We all know the network is a paramount component in a datacenter infrastructure, every major component depends on the network to function. Server/virtualization admins usually have to wait for network admins to provision new networks before they can go ahead and set up virtual machines for applications to run on. This can take hours to days or even weeks depending on the scale, complexity or requirements of the application.

Virtualization has been a very useful tool in the enterprise and its benefits cannot be over emphasized. More and more components of the datacenter are now getting virtualized and are becoming software defined. Enterprises are reaping the benefits of server and storage virtualization in their datacenters, however, a core component which connects all these together is still playing catchup: THE NETWORK!

Just like server virtualization where we create ‘virtual servers’ from an existing physical server, what if we could create ‘virtual networks’ from a physical network?

Enter network virtualization!

If servers and storage can be virtualized, the network should also be able to be virtualized right? Network virtualization involves creating the physical network in software which is similar to server virtualization.

In server virtualization, all the hardware of a server (CPU, memory, Network Interface Card) is recreated in software by a hardware abstraction layer called the Hypervisor. Similarly, in network virtualization, the physical network is represented in software using a ‘network hypervisor’ which then recreates network services in software (switching, routing, load balancing, firewall, VPN).

How does network virtualization (NV) work?

Similar to server virtualization, where logical instances of a server hardware is created in software(vCPU,vRAM,vNIC) NV creates a logical, virtual network by decoupling network functions from

the hardware that delivers them as logical network services –logical switches, logical routers, logical firewalls, logical load balancers, logical VPNs and more to connected workloads. These network and security services are delivered in software and require only IP packet forwarding from the underlying physical network.

VMware has a nice graphic (Figure 3) that explains the entire concept in a very simple manner.

Figure 4 illustrates, the workloads have no idea of the physical network but operate based on the configurations defined by the virtual network. In fact, the workload ‘sees’ the virtual network as a physical network. All networking services required by the workload is provided at the virtual network layer.

In figure 5, the traditional physical network is unaware of the existence of a virtual network. Rather, it ‘sees’ a simple Layer2 network frame passing through. This is because the virtual network uses the physical network as a simple IP forwarding backplane. To achieve this, network virtualization makes use of overlay technologies that sit on the physical network and interact with the server hypervisor. The two most popular overlay technologies are VXLAN and NVGRE.

Benefits of NV

Since server and NV are conceptually similar, it is usually assumed is to say both of them have similar benefits. This might not be totally true because they both aim to solve different problems. For example, one of the major benefits of server virtualization is hardware consolidation, less hardware will be needed to be purchased. For network virtualization, this might not be totally true because more switches will still need to be procured although less expensive ones.

SDx Central’s 2015 NV report listed the following as the main benefits of NV cited by organizations:

• Flexibility
• Scalability
• Reliability
• Operational cost saving
• Capital cost saving
• Others (Automation, simplified deployment, security)

Kindly share your thoughts, comments and parallel arguments about NV as we prepare the next part of the virtual series.

Author: Mohammed Ajibade