Exploring OpenStack’s SDN Connections

Pursuant to my last post, I will now examine the role of OpenStack in the context of software-defined networking (SDN). As you will recall, it was one of the alternative SDN enabling technologies mentioned in a recent article and sidebar at Network World.

First, though, I want to note that, contrary to the concerns I expressed in the preceding post, I wasn’t distracted by a shiny object before getting around to writing this installment. I feared I would be, but my powers of concentration and focus held sway. It’s a small victory, but I’ll take it.

Road to Quantum

Now, on to OpenStack, which I’ve written about previously, though admittedly not in the context of SDNs. As for how networking evolved into a distinct facet of OpenStack, Martin Casado, chief technology officer at Nicira, offers a thorough narrative at the Open vSwitch website.

Casado begins by explaining that OpenStack is a “cloud management system (CMS) that orchestrates compute, storage, and networking to provide a platform for building on demand services such as IaaS.” He notes that OpenStack’s primary components were OpenStack Compute (Nova), Open Stack Storage (Swift), and OpenStack Image Services (Glance), and he also provides an overview of their respective roles.

Then he asks, as one might, what about networking? At this point, I will quote directly from his Open vSwitch post:

“Noticeably absent from the list of major subcomponents within OpenStack is networking. The historical reason for this is that networking was originally designed as a part of Nova which supported two networking models:

● Flat Networking – A single global network for workloads hosted in an OpenStack Cloud.

●VLAN based Networking – A network segmentation mechanism that leverages existing VLAN technology to provide each OpenStack tenant, its own private network.

While these models have worked well thus far, and are very reasonable approaches to networking in the cloud, not treating networking as a first class citizen (like compute and storage) reduces the modularity of the architecture.”

As a result of Nova’s networking shortcomings, which Casado enumerates in detail,  Quantum, a standalone networking component, was developed.

Network Connectivity as a Service

The OpenStack wiki defines Quantum as “an incubated OpenStack project to provide “network connectivity as a service” between interface devices (e.g., vNICs) managed by other Openstack services (e.g., nova).” On that same wiki, Quantum is touted as being able to support advanced network topologies beyond the scope of  Nova’s FlatManager or VLanManager; as enabling anyone to “build advanced network services (open and closed source) that plug into Openstack networks”; and as enabling new plugins (open and closed source) that introduce advanced network capabilities.

Okay, but how does it relate specifically to SDNs? That’s a good question, and James Urquhart has provided a clear and compelling answer, which later was summarized succinctly by Stuart Miniman at Wikibon. What Urquhart wrote actually connects the dots between OpenStack’s Quantum and OpenFlow-enabled SDNs. Here’s a salient excerpt:

“. . . . how does OpenFlow relate to Quantum? It’s simple, really. Quantum is an application-level abstraction of networking that relies on plug-in implementations to map the abstraction(s) to reality. OpenFlow-based networking systems are one possible mechanism to be used by a plug-in to deliver a Quantum abstraction.

OpenFlow itself does not provide a network abstraction; that takes software that implements the protocol. Quantum itself does not talk to switches directly; that takes additional software (in the form of a plug-in). Those software components may be one and the same, or a Quantum plug-in might talk to an OpenFlow-based controller software via an API (like the Open vSwitch API).”

Cisco’s Contribution

So, that addresses the complementary functionality of OpenStack’s Quantum and OpenFlow, but, as Urquhart noted, OpenFlow is just one mechanism that can be used by a plug-in to deliver a Quantum abstraction. Further to that point, bear in mind that Quantum, as recounted on the OpenStack wiki, can be used  to “build advanced network services (open and closed source) that plug into OpenStack networks” and to facilitate new plugins that introduce advanced network capabilities.

Consequently, when it comes to using OpenStack in SDNs, OpenFlow isn’t the only complementary option available. In fact, Cisco is in on the action, using Quantum to “develop API extensions and plug-in drivers for creating virtual network segments on top of Cisco NX-OS and UCS.”

Cisco portrays itself as a major contributor to OpenStack’s Quantum, and the evidence seems to support that assertion. Cisco also has indicated qualified support for OpenFlow, so there’s a chance OpenStack and OpenFlow might intersect on a Cisco roadmap. That said, Cisco’s initial OpenStack-related networking forays relate to its proprietary technologies and existing products.

Citrix, Nicira, Rackspace . . . and Midokura

Other companies have made contributions to OpenStack’s Quantum, too. In a post at Network World, Alan Shimel of The CISO Group cites the involvement of Nicira, Cisco, Citrix, Midokura, and Rackspace. From what Nicira’s Casado has written and said publicly, we know that OpenFlow is in the mix there. It seems to be in the picture at Rackspace, too. Citrix has posted blog posts about Quantum, including this one, but I’m not sure where they’re going with it, though XenServer, Open vSwitch, and, yes, OpenFlow are likely to be involved.

Finally, we have Midokura, a Japanese company that has a relatively low profile, at least on this side of the Pacific Ocean. According to its website, it was established early in 2010, and it had just 12 employees in the end of April 2011.

If my currency-conversion calculations (from Japanese yen) are correct, Midokura also had about $1.5 million in capital as of that date. Earlier that same month, the company announced seed funding of about $1.3 million. Investors were Bit-Isle, a Japanese data-center company; NTT Investment Partners, an investment vehicle of  Nippon Telegraph & Telephone Corp. (NTT); 1st Holdings, a Japanese ISV that specializes in tools and middleware; and various individual investors, including Allen Miner, CEO of SunBridge Corporation.

On its website, Midokura provides an overview of its MidoNet network-virtualization platform, which is billed as providing a solution to the problem of inflexible and expensive large-scale physical networks that tend to lock service providers into a single vendor.

Virtual Network Model in Cloud Stack

In an article published  at TechCrunch this spring, at about the time Midokura announced its seed round, the company claimed to be the only one to have “a true virtual network model” in a cloud stack. The TechCrunch piece also said the MidoNet platform could be integrated “into existing products, as a standalone solution, via a NaaS model, or through Midostack, Midokura’s own cloud (IaaS/EC2) distribution of OpenStack (basically the delivery mechanism for Midonet and the company’s main product).”

Although the company was accepting beta customers last spring, it hasn’t updated its corporate blog since December 2010. Its “Events” page, however, shows signs of life, with Midokura indicating that it will be attending or participating in the grand opening of Rackspace’s San Francisco office on December 1.

Perhaps we’ll get an update then on Midokura’s progress.

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