Featured Interview: SDN Startup Plexxi’s CEO, David Husak

Featured Interview with David Husak Plexxi CEO

SDNCentral: Plexxi has been highlighted as one of the key SDN startups to watch. For the few readers in our community who might not be completely caught up yet, can you provide a brief description of Plexxi, what problems you’re solving and the solutions you bring to the table?

Dave:Plexxi is an enterprise networking startup. We are delivering the hardware and software products necessary to implement Affinity Networks. An Affinity Network allocates its capacity and functionality directly from user application and tenant hosting workloads.  This results in a system that has transformative scale, performance, and efficiency advantages compared to conventional enterprise network architectures.”

SDNCentral: What is Affinity Networking?

Dave: “Networking today is disconnected from the workloads it serves.  What if we could build networks that understood the concept of how these workloads communicated and what network services they need, directly?

Affinity provides the abstraction, the network meta-data, to describe the application-driven network requirements. This is a radical departure form conventional networks, where that information is buried in the device- and protocol-specific configuration details of hundreds or thousands of disparate devices. This allows us to deliver an infrastructure that doesn’t require you to define how it works – just what you expect from it.

By the way, and this is just as important… The Affinity abstraction not only drives the automated orchestration of network capacity, but also provides the benchmarks to quantify the performance of the network against actual application requirements.”

SDNCentral: Can you give me an example of affinity?

Dave: “A common example is Hadoop clusters. Successful, reliable Hadoop deployments rely on correctly provisioning Rack Awareness among slave Data Nodes. When defined as a Plexxi Affinity group, this complexity is essentially eliminated–we can make a “rack” any size you want.”

SDNCentral: What’s your definition of SDN? Is Plexxi an SDN company?

Dave: “That you need to ask for our definition of SDN is telling… That said, one common thread among various SDN definitions is that SDN gives us the opportunity to abstract the operation of a network as a single system. There are powerful optimizations that using SDN affords us that would be impossible to do with conventional layered, distributed-protocol stacks and switched-hierarchical physical topologies.

But to fully realize the promise of SDN, we have to get the abstractions correct.”

SDNCentral: So is Plexxi an SDN company?

Dave: “Yes. We are one of a very small number of companies employing SDN to deliver a complete enterprise-networking product. But, the real value of our solution is in what Affinity Networks deliver to our customers, not that we used SDN to build it. The fact is this: SDN is a methodology, not an end state.”

SDNCentral: What prompted you to bring DWDM optical technology to the datacenter?

Dave: “In essence, it is the same set of motivations that brought WDM optical technology to the telecom network decades ago:

Firstly, in order to build software-defined, orchestrate-able network topologies, we needed a technology that can define network connection reach and capacity dynamically under software control.

Secondly, when we contemplate modern datacenter scale, performance and traffic pattern requirements, it is clear that the switched-hierarchical network architecture is nearing the end of its useful lifetime. However, when you consider the properties of optical switching—it is well-established that the price-power-speed performance advantage of photonic switching is approximately 20,000:1 when compared to electronic switching—it is clear the datacenter networks must harness this advantage to meet those requirements. And, our controller and our switches are the first commercial products to do so.”

SDNCentral: So it is true that you’re changing the standard datacenter topology with ToR and core switches and making it a big optical ring with off-ramps into Ethernet? Do you believe that kind of east-west bandwidth is needed?

Dave: “Yes, Plexxi is bringing a new physical connection topology to datacenter networks. A ring is the simplest, baseline topology we support, and we will be extending that to even higher-scale topologies when we introduce additional switch products later this year.

It is certainly the case that 21st-century application and tenant workloads are far more dependent on server-server (east-west) capacity than was the case when the hierarchical-switched architectures were devised. A Plexxi Affinity Network can manifest those connections directly (with inherent improvements in reliability, latency and security).”

SDNCentral: Given the above, does the Plexxi gear play nice with existing infrastructure?

Dave: “All of our deployments are side-by-side traditional networking gear. Our access interfaces are conventional Ethernet interfaces.”

SDNCentral: What’s your secret sauce that’s hard for someone else to replicate? Aren’t you also trying to leverage merchant silicon? 

Dave: “Our secret sauce has two key ingredients. One is the novel WDM implementation that I talked about previously.

The second is the set of algorithms in our controller that take affinity information (provided through our Affinity API), and use it to render forwarding topologies, taking maximal advantage of the flexibility of the underlying switch fabric and the optical/electronic performance benefit.

We call this process “fitting” and it produces considerably better topologies with lower resource consumption than the topology-computation algorithms used in layered protocol stacks and most other SDN controllers.”

SDNCentral: How does that benefit datacenter operators? In comparison with current gear, can you prove the Plexxi approach is significantly better? What about the cost model?

Dave: “Our controller is a single administrative touch point that automates network configuration directly from the affinity abstraction, in most cases freeing the network administrators entirely from manual network engineering.

Adopting Affinity Networking also means that an operator can move beyond managing MAC addresses and servo the network configuration directly to the attached systems, whether physical or virtual, along with their workload requirements. That is, we can “close the loop” and really know, from moment to moment, that those workload requirements are being satisfied.

We also build datacenter networks without the capital and operating expense of aggregation and core switching tiers. Particularly with scale, this is a considerable cost savings.

Ultimately, a challenge we all face is in quantifying the cost benefit of applications that just work better.”

SDNCentral: Is the affinity model that you propose good for all workloads? Where does it break down–what workloads will it not work for?

Dave: “The Affinity model is general and broadly applicable. And the concept of affinity is nothing new. Every time an administrator manually assigns rack numbers to Hadoop Data Nodes; allocates capacity for a flash storage tier; or creates a multicast group… affinity is being expressed (albeit indirectly, and translated imperfectly through manual network engineering, distributed device configuration and protocol convergence).

The difference is that now, with Affinity Networks, users have the ability to encode and manifest those affinities directly through an API. And that renders them truly portable and scalable.”

SDNCentral: What role does OpenFlow play in your solution? What’s your view of the ONF?

Dave:OpenFlow is not in our products today. We don’t have any real religion about the underlying protocols we use, but we believe the industry is still a ways off from a fully functional, robust, standardized southbound interface.

We are active in the process. Plexxi has been a member of the ONF since its formation, and we are committed to the ONF’s continued development and promotion of SDN and Open Networking.”

SDNCentral: Can you actually effectively manage the different wavelengths in your DWDM solution? What happens if the number of flows goes up and you run out of wavelengths to tie them to?

Dave: “Yes. It is important to understand that while we employ WDM technology, we have not used it to build a “telecom-style” architecture. Our solution is tuned (pun intended) to datacenter traffic patterns.

So, in our architecture, the arrangement and reach of wavelengths is flexible, and it is not necessary that there is a fixed correspondence between wavelengths and flows.

Our fitting algorithms compute both the WDM configuration and flow mapping automatically.”

SDNCentral: Doesn’t introducing a new model of management make life harder for the datacenter operators? Will it play nice with existing network management solutions or orchestration solutions?

Dave: “We believe that visualizing the performance and operation of networks through the lens of application and tenant affinities is a powerful abstraction that makes life considerably easier.

And, yes, we do play nice with existing network management frameworks, and our switches implement the conventional embedded management interfaces and protocols.”

SDNCentral: BTW, you may have seen the mention of Daylight recently on SDNCentral. What’s your take on that and will Plexxi be playing a role?

Dave: “Daylight will help the industry through the release of a considerably broader set of protocols relevant for SDN, as well as providing a more complete reference controller implementation. It can also help the industry focus on more of the real customer problems: reduction of complexity in infrastructure workload automation.

It’s too early for us to speak definitively about contributions to Daylight, but we believe there are a number of elements of Affinity Networking that unlock the value of affinities across a wide range of IT infrastructure.”

SDNCentral: What do you predict for SDN in 2013? Will this be the year SDN actually gets real?

Dave: “SDN is real today. We have deployed it in our customers’ production networks. But, I expect that you are really asking about when the “tipping point” will occur where SDN becomes the normal operation model. There is that Bill Gates quote that probably applies here: “We always overestimate the change that will occur in the next two years and underestimate the change that will occur in the next ten.”

I am confident that the enterprise networking industry is at an inflection point where, for the first time in more than a decade, there is reason to look forward instead of back. By harnessing the power of state-of-the-art algorithms, computation and storage capabilities, and optical switching technology, we will be building networks with unprecedented scale, performance, utility and ease-of-use.”

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