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Software Defined Networking – A Paradigm Shift
Now it's all about orchestrated service delivery
By: Kapil Raval
Feb. 19, 2013 06:30 AM
The networking industry has gone through different waves over last 30+ years. In the '80s, the first wave was all about connecting and sharing; how to connect a computer to other peripheral devices and other computers. There were many players who developed technology and services to address that, e.g. Novell, 3Com, Sun, IBM, DEC, Nortel. Across the industry, small islands of various protocols were created with multiple gateways to bridge them.
Now, it is all about orchestrated service delivery which requires standards-based open approach. According to Gartner reports on Emerging Technology Analysis and Key Issues for Communications Strategies, a) over 50% workloads will be virtualized by the end of 2012 thanks to Cloud computing, and b) more than 80% of traffic will be server-to-server by 2014 due to federated applications and virtualization.
In this article, I attempt to highlight why we have reached limits of current network technology, how Software Defined Networking will lead the next wave of innovations and its benefits to the IT industry. Today, network elements like switches and routers have resident software in each box. The software in the box provides intelligence using distributed algorithms to decide how each packet should be handled by it. In order for the entire network to function properly, the software in each box must work in coordination with other boxes. This approach has served us well so far.
The coordinated distributed algorithms however make it difficult to introduce a change on the fly. We have to reconfigure the embedded software on all network components (often called boxes) to implement any change. On the other hand, the wave of virtualization demands flexible, adaptive and nimble networks. This wave exposes limitations of the current networking approach, which is inflexible and protocol-heavy. As distributed algorithms are used, not one box has a global view of the network. This results in over provisioning at the time of designing and guess-work while trouble-shooting. For large cloud deployments, compute and storage environments can be virtualized and consumed easily but because of the limitations of networks, its full potential is not realized.
Typically, a network administrator spends a lot of time planning and then configuring the network components with changing business requirements and varying network traffic. Network administrators learn a lot by trial and error and the resulting expertise based on experience is limited to the experienced few.
Another interesting point is that ONF wants to do as little standardization as possible to encourage creativity. At first it sounded a bit conflicting but ONF looks at the software industry and tries to follow it by taking its best practices. When you look at the software industry, there are fewer standards than the network industry and it has created more innovations and jobs than the network industry. The Network industry has too many protocols defined and standardized, resulting in more complexity and fewer innovations. Academicians are influencing ONF and ensuring that we don't end up with another rigid, inflexible and protocol heavy networking world. ONF has 66 members today and its membership costs $30k/year. This is relatively high compared to other such bodies and the reason could be to ensure that only genuinely interested parties become members. We know that breakthrough innovations would come from small start-ups, some of whom would find it difficult to spend so much for the annual membership. On the other hand, ONF ensures that the development made as part of their body is made available to all members at no charge or royalty etc. One would end up spending more than $30k in lawyer's fees to get the royalty arrangements sorted out.
Google embraced OpenFlow very early on. Google's inter-datacenter production network, largest in the world by traffic, runs on OpenFlow and SDN. Google proved that OpenFlow based networks can scale and deliver its promise. The biggest use case, according to Google, for Central controllers is the fact that we can do re-routing, anticipating an event, e.g. if we know that we are introducing a new service which will lead to traffic load, we can pre-provision network in a way to best optimize infrastructure resources. If a small business, say a Flower shop, expects more traffic and compute power on a Valentine day, it is easy to have compute and storage power made available with standard virtualization technology available today. But to make network resources available on demand is challenging. This is where an OpenFlow controller controlling switches can easily provide necessary bandwidth and then tear it down or redirect the network resources for other requests. Google example is impressive but one could argue that how many enterprise customers could afford or dare to do what Google can do. Moreover, just because it made a business case for Google does not mean that it can make a business case for everyone. Each customer will have to evaluate their network, future growth requirements etc and see if there is a positive business case.
Some vendors want to have API's well-defined for applications to leverage OpenFlow controllers or have more protocols supported. It is prudent on the part of ONF not to define and standardize too much and let the market define what an acceptable standard is. It is important to keep OpenFlow protocol unrestricted by defining and standardizing not more than what is absolutely required. This will fuel innovations.
OpenFlow protocol is in its infancy but it has generated tremendous interest from customers, researchers as well as vendors. One can argue that it is not fully matured or ready for prime time but most agree that it will change the network industry fundamentally. It will make the industry more flexible, nimble and drive more innovations. This train has left the station while some debate that its destination is not well-defined or its ETA is not known. The hardware vendors will have to accept the fact that networking hardware will be commoditized just like servers and storage. OpenFlow/SDN, for sure, opens up opportunities for different network based applications. This is where current vendors will have to focus on to continue to play a major role in the future. Network administrators will not be spending hours reconfiguring switches and routers. They will have to get skilled on how to control, manage, test and implement changes from a central controller.
Although the OpenFlow protocol is defined, there are not many vendors in the market supporting its latest version 1.3. Moreover, there is a lack of tools to test, monitor and manage this new environment. HP and other major vendors have openly embraced OpenFlow and are investing in it. HP was one of the first major network vendors to invest in this area, with 60+ deployments of 16 different switches supporting OpenFlow. HP is also leading one of the task forces of ONF to evolve the OpenFlow protocol. With its traditional strength in IT performance & operations (test, monitor and manage) management and telecom OSS, HP is well-positioned to deliver a complete future-proof infrastructure solution, (consisting of server, storage, networking, software, security and analytics) for enterprise IT as well as telecom service providers.
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