Network Infrastructure

An Architecture for the Application Age: SDN Turns Networking Upside Down

By Paula Bernier, Executive Editor, TMC  |  March 15, 2013

This article originally appeared in the March 2013 issue of INTERNET TELEPHONY.

SDN is considered by many to be one of the most important, and potentially disruptive, developments in networking since the rise of the Internet. To date, networks and connectivity have come first, and applications have followed. The software-defined network turns this model on its head, approaching networking from an application- and services-first standpoint. 

“To me, [SDN] is one of the most interesting pivot points in networking I’ve seen pretty much since the Internet,” said Eve Griliches, vice president of optical research at ACG Research, a panelist at the recent SDN Precon at ITEXPO Miami.

 The Concept

This architecture separates the control and data planes of the network, she explained. But Griliches added it’s really about much more than that. SDN is about looking at active flows in the network, understanding the requirements of those different flows, and using the network to provide those flows with the appropriate bandwidth and other network resources.

What SDN will do is open up the network in the way we’ve opened up the applications on the iPhone to enhance what we are doing in the network, she said. This view of the network is very disruptive considering we’ve traditionally built networks from the ground up, with connectivity at the forefront.

“It’s an entire paradigm shift here, and people are going to have to think very differently with SDN,” she said.

SDN is a more logical approach to networking than we haven’t really been able to do before, according to Griliches. However, this kind of thing is now possible due to the algorithms that enable us to better understand flows, and due to the decreasing costs of hardware. Griliches believes that at least half of enterprise and wide area networks will leverage SDN in some form within about five years.

Users and Applications

David Krozier, principal analyst of network infrastructure at research firm Ovum, told INTERNET TELEPHONY there are a significant number of data center SDN deployments today because every major university is participating in one of the research network implementations of software-defined networking using OpenFlow. It doesn’t take much work to deploy this kind of thing, he added, saying you just get a couple of switches, some software, a connection to the university network, and you have an SDN lab.

In fact, he said, HP alone has more than 60 such deployments.

Meanwhile, enterprise deployments of SDN are “very small,” said Krozier, and service providers are using, or at least testing SDN.

 “NTT has been a big proponent of SDN in general, and NTT actually as far as I can tell is offering the first commercial service based on SDN,” he said. “The service is called enterprise cloud and uses an OpenFlow-enabled network to migrate virtual machines between data centers. It’s something that’s being offered in Asia today.”

AT&T (News - Alert) has also deployed Nicira software, Krozier added, but he said he’s not clear about exactly what the telco is doing with it. The telco could’ve just been for trial purposes, he said.

As for Verizon (News - Alert), Krozier said that telco is leveraging SDN technology to control the quality of experience of video on wireless networks. The service provider is using SDN to control the quality of experience for video delivery.

“There’s a lot out there about SDN and [the] data center, but I think where SDN will have a lot of impact in carrier networks is in wireless networks,” Krozier said.

However, probably the biggest name driving the SDN movement is Google (News - Alert).

Google already is using an SDN-like solution, based on OpenFlow, that it developed itself at significant expense to more effectively interconnect its data centers, according to a report by Woodside Capital Partners, which notes that Verizon is also a key proponent of SDN. “We view the Google application as a good proof of concept for SDN and the OpenFlow protocol, rather than a commercially viable solution,” according to an August report from the Silicon Valley-based investment banking firm.

Suppliers and M&A

Of course, there are plenty of SDN solution providers out there. The list includes Big Switch Networks (News - Alert), Embrane, ConteXtream, PLUMgrid, Midokura, and Pica8, among others. And Alcatel-Lucent has launched a business called Nuage to address the SDN opportunity.

But the number of little guys in the SDN space is getting smaller as some of the bigger names in networking snap up what have recently become important assets.

VMware Inc. in July cut a deal to buy Nicira Inc. for $1.26 billion. That same month, Oracle followed suit with its purchase of privately owned Xsigo. (Nicira products are already in use by AT&T, DreamHost, eBay, Fidelity Investments, NTT and Rackspace (News - Alert) to accelerate service delivery. Meanwhile, the Xsigo solution has been deployed at hundreds of enterprise customers including British Telecom, eBay, Softbank and Verizon.)

Things picked up on the SDN acquisition front again in November, with Brocade revealing plans to acquire Vyatta, and Cisco announcing its intent to buy privately held Cariden Technologies, which reportedly has done some SDN work. (Brocade at the time of the deal noted that Vyatta is shipping products today and is developing a next-generation, on-demand network OS that delivers advanced routing, security and VPN functionality for physical, virtual and cloud networking environments. Cisco said Cariden’s IP/MPLS planning and traffic engineering software is in use by many major service providers.)

Then, in December, Juniper Networks quietly made its move to bring SDN startup Contrail Systems into the fold. A month later, Juniper publicly announced its software-defined networking strategy at a partner event.

“This transformation is one of the biggest things we will ever see,” said Bob Muglia, executive vice president of the software solutions division at Juniper Networks, referring to SDN.

Infrastructure Angle

Fellow network equipment supplier Cisco, meanwhile, seems to be downplaying the importance of SDN.

Shashi Kiran, senior director of data center and cloud networking at Cisco in late December told INTERNET TELEPHONY that the concept of SDN is nothing new. Elements of SDN are things that Cisco has been doing for some time, he said. However, he went on to say that to address the requirements SDN aims to meet, Cisco is investing in ASICs and opening up its gear – from the smallest router to biggest products – via developer kits. The company also is investing in its own controller, which supports OpenFlow, he said, adding that really is what the SDN model is about.

Kiran also points to the Cisco Nexus 1000V, which he describes as an overlay solution that mostly works in cloud/virtualized environments, and uses OpenStack and RESTful open source technology. Cisco’s onePK is also part of the company’s Open Network Environment, which involves SDN.

Responding to recurring commentary that the new software-focused view of networking that SDN espouses will negatively impact the business of network equipment companies, and Cisco in particular, Kiran commented that the network recently has become far more central to the IT infrastructure than perhaps at any time in the past, and trends like SDN and open networking are just enforcing that fact.

“SDN put spotlight on the strategic nature of networks all over again,” said Kiran.

Juniper CTO Pradeep Sindhu expressed a similar sentiment during the SDN strategy announcement by his company, in which he – in what seemed an agitated tone – reminded analysts and reporters that physical infrastructure will continue to anchor even the most software-driven networks.

Houman Modarres, senior director of marketing in Alcatel-Lucent’s core networks group and a speaker at TMC’s SDN Precon, noted that his company as of late January hadn’t yet announced its SDN strategy, but he did say that Alcatel-Lucent believes allowing apps to make requests of the network is an important step in making the network side as responsive as the compute side.

Today, the network is not a product, he added, it’s a means to an end. There have been strides in recent years on the Layer 2 network virtualization front that made heads turn, he added, indicating that may have fueled interest in SDN. But rather than getting excited about a new buzzword, Modarres indicated that what we should be talking about is where we are going, why, and how (and if) SDN can help us get that. The answers for different organizations will vary, he added. 

Huawei, which sells everything from wireless handsets to carrier network equipment, has embraced SDN, said Mike McBride, as a fine-grained way to introduce new services and to offer policy and control that the company’s service provider customers seek. McBride, a principal engineer within Huawei’s network technology CTO office and a representative of the ONF, was also a panelist at SDN Precon.

“We’re fully on board [with SDN],” he said.

That said, Huawei customers have spent a lot of money on their existing equipment, so the vendor wants to enable its network elements to accept blades with OpenFlow chipsets, he added. That way, he said, Huawei’s service provider customers can implement OpenFlow and SDN in an incremental way.

ONF recently created a migration working group to address how to transition non-OpenFlow equipment to support OpenFlow, said McBride, who is doing double duty these days, representing both Huawei and the Open Networking Foundation. The industry group is working off the Google model, he said, noting that Google has created an OpenFlow-capable new WAN, and is slowly migrating its data centers to that WAN.

That’s been very successful for Google, and it’s good for the ONF, he added.


So just what are the components that will make up the software-defined network? Well, answers vary.

As ACG Research’s Grilitches sees it, the SDN architecture includes switching elements that are optimized for fast switching but that do not have a higher order intelligence; and a controller, which is centralized, and controls the switches and can be used to manage network resources and performance based on the apps.

A northbound interface on the controller can allow for apps to hook in, she added.

Ping Pan, chief architect at optical transport switch company, Infinera, and a speaker at SDN Precon, believes there are three functions of SDN: the ability to provision to the needs of the applications; configuration; and monitoring. As a result, he said, the transport network will be more visible to the applications.

“Applications need some resources, and networks need some information,” said SDN Precon panelist Nils Swart, director of technical marketing at Plexxi, a software-defined network startup.

Plexxi offers a controller that takes information from applications and uses that data to optimize the underlying network. The company also sells top-of-rack, high-capacity switches so data center operators can adjust uplink capacity based on what applications require. The company, Swart explains, removes network complexity by delivering control via a single pane, and rather than bolting on its solution to existing routers and switches, it uses hardware in a ring topology with software that handles the control.

“We believe SDN is absolutely already here,” said Swart.

In announcing its SDN strategy, Juniper executives described what it sees as the six principles of the software-defined network. SDN, according to Juniper, entails cleanly separating networking software into separate management, services, control and forwarding layers or planes. It requires the centralization of the appropriate aspects of management, services and control software to simplify the network and lower operating costs. It involves using the cloud to allow for flexibility and scalability. It will require a platform for network applications, services and integration into management systems to enable new business solutions. The industry will have to standardized protocols to allow for vendor interoperability.

And, Juniper believes, network operators and their partners will have to broadly apply SDN principles to all networking and network services including security from the data center and enterprise campus to the mobile and wireline networks used by service providers.

Juniper then laid out its product strategy to address those six principles. First, Juniper executives said, the company will centralize network management, analytics and configuration functionality to provide a single master that configures all networking devices. The Juniper Junos Space applications put customers on that path today, according to the company.

Then, Juniper will enable its customers to extract networking and security services from the underlying hardware by creating service virtual machines based on industry-standard x86 hardware. Pulling services and network management capabilities out of network elements and instead running them as virtual machines on x86 servers will allow for “truth in management” and will mean that “the device is no longer the master,” Muglia said.

JunosV App Engine, which becomes available this quarter, and Juniper’s new software licensing program, which enables licenses to be expanded to x86 platforms, will help enable that.

A centralized controller, which Juniper got via the Contrail acquisition, is the third key tenet of Juniper’s SDN strategy. That, the company said, will allow multiple network and security services to connect in series across devices within the network. Juniper refers to this capability as SDN Service Chaining, a feature it expects to deliver starting next year via the Contrail solution and a next-generation version of the JunosV App Engine.

“Service chaining functionality is crudely accomplished in today’s physical world using separate network and security devices,” according to the Juniper statement. “With SDN Service Chaining, networks can dynamically respond to the needs of the business. This step will dramatically reduce the time, cost and risk for customers to design, test and deliver new network and security services.”

Like Cisco, Juniper also tells its hardware optimization story when discussing SDN, pointing specifically to its MX Series and SRX Series products, which it says will evolve to support Service Chaining. And Juniper’s Muglia said that while layer 7 services can run on general purpose x86 servers, functions like forwarding packets and flows may be best served by ASICs, which are optimized for that kind of thing and can deliver an order of magnitude better performance for applications and services that require it.

While many industry players will tell you they consider OpenFlow as a key component of SDN, Muglia commented that it’s a protocol that Juniper will support, but added OpenFlow is just a small piece of SDN – and not a very important one.

It seems that at least one analyst agrees.

“One of the definitions [of SDN] flows around the Open Networking Foundation and OpenFlow,” said Krozier of Ovum. “I think that definition is rather restrictive. I really see SDN as an architectural concept that includes abstraction of the physical network, programmability, network virtualization. I think it’s really a movement toward a much more flexible network.”

But getting to this flexible network looks to be a significant challenge, and one that, according to Sean Blakley, managing director of WCP Research and an SDN Precon speaker, presents a significant opportunity for someone to step in and integrate the different pieces of the SDN puzzle.

Edited by Braden Becker