About 10 years ago, a few smart folks invented “Software Defined Networking” or SDN for short. SDN promised to “separate the data plane from the control plane”, but another objective was to break free from vendor lock-in. They wanted SDN to enable a network where one can design the network, manage it and monitor it without any dependency on a specific switch vendor. The concept was great, but the implementation started with OpenFlow, which for many reasons didn’t work so well and today is being used in a very limited way.
Let’s pause and see what happened with the other elements of the data center, compute and storage:
SDN is live and kicking, but what is SDN? – The answer depends on who you ask.
If you ask those who invested in OpenFlow, they will say SDN=OpenFlow, but there are not many of them left.
If you ask the incumbent switch vendors, they will give you a very comprehensive story about a single pane of glass, micro-segmentation, multi-cloud, etc. but how is that related to SDN? It’s hard to say, but maybe it’s the fact that they are selling you their proprietary controller, which sounds a lot like those SDN OpenFlow controllers? It’s hard to tell, but for sure the “incumbent SDN” doesn’t separate the control plane from the data plane, and doesn’t support a heterogeneous vendor switch deployment …
At this point I had to run a sanity check and checked Wikipedia, here’s the definition of SDN as of March 8, 2020:
Software-defined networking technology is an approach to network management that enables dynamic, programmatically efficient network configuration in order to improve network performance and monitoring making it more like cloud computing than traditional network management.
I must say that Wikipedia’s definition is very close to what I’d consider SDN today.
In order to achieve the goal SDN was created for, we need to focus on management. Not a single-vendor proprietary management offering, but a way to manage multiple vendors’ switches in a standard and simple manner.
SDN is a modern network, that is managed through an automated API rather than manually through a CLI, enabling easy configuration orchestration and management, as well as a simple way to monitor the network.
SDN was invented to break free from lock-in, allowing organizations to build the same management infrastructure once and use it with various networking vendors.
Many organizations are implementing real SDN networks today, that leverage Open Ethernet, standard Linux tools, ONIE based switches and enable choice of hardware. But today, the vendors shouting the term “Software Defined Network” the loudest, are actually those who build the most proprietary sole-source, vendor lock-in switch offerings.
So, don’t be fooled. Make sure when you choose a SDN, you can choose a switch vendor too!
Read more about Mellanox Spectrum Ethernet Switches: https://www.mellanox.com/products/ethernet-switches