Guest blog by Greg Nehib, SP Product and Solutions Marketing

I like to think of virtualization as an expanded networking toolkit, providing us with additional options to get the job done. It's almost like when cordless tools entered the consumer tool market. You could take the cordless tools anywhere and use them in new and exciting applications. But there was a key drawback that I'm sure you remember. The early cordless tools had a limited effective power range. Over the next decade or two, battery technology improved and there were fewer power related drawbacks to going cordless.

A few similarities exist in the network functions virtualization (NFV) space. Ithink that most network functions outside of physical connectivity (optical, copper, wireless, etc.) could be virtualized. A growing number have already been virtualized. The Cisco count alone is up to 49. Network operators and equipment manufacturers are asking themselves which network functions should be virtualized for different service types and on what scale? In some cases they are also thinking about what they would have to give up in performance or functionality to virtualize a network function and gain in flexibility or workflow portability.

Enter the virtual router. The name describes it fairly well. It's the functionality of a purpose built physical router that has been virtualized in software to run on general purpose X86 server hardware from any hardware vendor. That sounds really exciting, but there are a few primary drawbacks:

1. One drawback is throughput. Since the current array of available X86 server hardware was built for compute applications, its strength lies in the number of compute transactions it can process and not in overall networking throughput. Bandwidth throughput in excess of 20 Gbps to 40 Gbps is not in the "sweet spot" of the capabilities of today's best high-end multi-core server.
2. Another drawback of running a virtual router on an X86 server is performance. If you emulate your favorite router's operating system onto a high-end server via virtual machines, throughput will also be affected by serialization. That means that by turning on commonly used features like Hierarchical Quality of Service (H-QoS), traffic management, and Access Control Lists (ACLs) and by running a variety of packet sizes through the router you will begin to see a performance degradation proportional to the complexity of the service mix.

Please watch this short video explaining the new innovations of the Cisco IOS-XRv 9000 virtual router:

 The "hardware in software" innovation appears to be mission critical, but you might still be wondering why anyone would want to deal with the potential scalability drawbacks of a virtual router? Why not just stick with your current purpose built physical routers? The answer is flexibility. As end user applications become more on-demand and as the number of devices in the network grows with the Internet of Everything (IoE), it becomes increasingly difficult to predict network growth. And while predicting network growth in the Core of your network might be manageable, predicting network growth on the Edge or in the Access may be virtually impossible (I couldn't resist using that phrase). Imagine the NCAA Final Four coming to town. Not just the increased video service requirements, but also all the associated applications leveraging this media can be overwhelming to most network locations. And just as quickly as they came into town, they're gone. The extreme bandwidth requirement moves on to the next location and the next media frenzy.

I've enjoyed my cordless drill. Virtual routers are also a great tool to have in your networking toolkit. It's clear to me that virtual routers will have fewer drawbacks over time. Much like the lithium battery revolutionized the cordless consumer tool market, innovations like the "hardware in software" capabilities of IOS-XRv 9000 described in the video above will expand the use cases of the virtual router. I still have a big gasoline powered lawnmower and I'd recommend that you hold onto your ASR 9000 physical routers for a few more decades too. Physical routing and virtual router technologies are complementary, like tools in a networking toolkit.

Have questions or comments about the IOS-XRv 9000? Tweet us at @CiscoSP360.