Network Virtualization Key to IaaS Clouds

Grazed from Virtualization Review. Author: Ben Cherian.

Network virtualization delivers network services in a more scalable, manageable, and fault-tolerant manner than traditional networking can deliver. For this reason it is gaining traction among cloud architects, rapidly becoming a “must have” component of IaaS clouds. So, what is network virtualization? When cloud architects speak of network virtualization they are typically referring to overlay-based network virtualization. With OBNV, network functionality is abstracted away from the underlying physical network and into the software.

What this means is that network services like virtual switching, routing, and firewalling can happen in software at the “edge” of the network rather than relying on the physical core of the network to have this functionality available. What this means in practice is that a cloud architect can design the network with basic low-cost hardware, while providing higher layer functions in the software, where advanced switching, routing and firewalling can be be managed with greater ease and precision. Why wouldn’t I just use traditional networking in the cloud? When building an IaaS cloud, traditional networking faces two serious limitations: scalability, and management and automation…

Scalability
In an IaaS cloud, it’s very difficult to properly plan for the size of your tenant’s deployment. Tenant Alice might initially have five VMs in the first month of operation but could grow her VM count to 1,000 if the initial deployment is successful. Take the example of a router. Whether you use a physical device or a virtual machine to give Alice her router, the size of the router will need to change based on the number of VMs that are being serviced. Upgrading the router will invariably introduce service interruptions for the tenant. Furthermore these traditional devices aren’t designed to deal with the micro-granularity and high churn that cloud environments require of them…

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