Interest in software-defined networking (SDN) kicked in last year when the enabling OpenFlow standard was announced and the Open Networking Foundation (ONF) was formed in order to take it forward into the real world. I don't claim to have any networking expertise, but I like developments that change the rules of the game, particularly a game that hasn't changed much in the last 40 years. I wrote positively about SDN at the beginning of the year and a few weeks later Dan Pitt, Executive Director of the ONF gave a presentation at NetEvents in Garmisch, Germany. The SDN was also debated by a panel of experts there, and their reaction was lukewarm: "Yes, it's an interesting development but don't hold your breath on deployment."
This reaction was understandable because replacing all the kit that is out there in the Internet will take time, and powerful vendor agendas will kick in. But right now there is a compelling need to consolidate the number of data centers, and an SDN would seem to be an ideal way to interconnect them, thereby creating cost-effective, private clouds managed end-to-end by IT. Samsung, for example, had over 120 centers worldwide and now they have fewer than 10. A private cloud that employs Ethernet switches enables interconnection.
SDN has become one of the hottest topics in IT. The Dell'Oro Group predicts 17-fold SDN market growth within five years, reaching $2.5 billion by 2016. Stats like these may turn out to be overly optimistic, but we are moving towards a mobile computing environment, and mobile data is driving the need to upgrade the networks of mobile operators. It's not simply a matter of increasing capacity: high-density, high-speed, low-latency switches are required to manage subscribers as well as their devices and apps, particularly real-time apps like conducting financial transactions from your smartphone. And that is where next-gen Ethernet switches come into the equation. In wide-area SDN environments, they can be programmed in a similar way to that of the LAN.
Extreme Networks has been making a series of SDN announcements. Their Ethernet switches support OpenFlow, and Deutsche Telekom (a somewhat cautious MNO) has bought the company's Black Diamond X8 product to manage the mobile data traffic that their 57 million customers are generating. And they have also been deployed at an Internet Exchange operator to enable on-demand, special services for the London 2012 Olympic Games. The deliverable included software applications.
Right now the enterprise sector is lagging, but Extreme is predicting an accelerated take-up since the need to handle and manage data from mobile employees is very similar to that of mobile consumers. That said, there are early adopters in health care, government and universities.
On the other side of the coin, the MNOs are adopting the cloud model and are looking to become cloud service providers, and some have Amazon-type ambitions. Whether that ambition will be realized is debatable, but OpenFlow and OpenStack, (see sidebar "SDN Summary" on Page 2 of this piece) are the developments that would enable them to deliver efficient, cost-effective services.
A Linux-like movement
Extreme's Doug Willis was in London recently and we talked about SDN going forward. He is predicting a near-term change around OpenFlow. This protocol will result in SDNs being standardized, which in turn will drive market demand for programmable networks. That's kind of obvious, but five years out he sees SDN redefining networking because the model is close to that of the layered, virtualized architecture of mainstream computing.
We've advanced from the proprietary, big-box dumb terminal environment to the open client-server model and now we are in a mobility era, but the Net has been restrained by the limitations of proprietary, monolithic routers and switches. OpenFlow, as the name implies, opens things up, so we should think of SDN as a development that enables a Linux-like movement, one that will remove the current mainframe-type lock-in and eventually result in the development of Android-like applications.
When I asked if Extreme would play in that sandbox, the answer was a qualified No. The company isn't big enough: that development will have to come from heavy hitters like Google and Facebook and maybe a few innovative MNOs. This is a software-centric development, but of course there will always be a need for hardware. However, the company has enabled its ExtremeXOS product system to function as the networking equivalent of the Linux computing operating system.
Virtualizing Networks
The cloud-computing model makes more efficient use of computing resources. Servers located in data centers are virtualized in order to decouple and isolate virtual machines from the underlying server hardware. In most cases, traffic flows between data centers and users over a regular network, e.g. a VPN. However, logic would seem to indicate that a virtual network would perform this task in a more efficient way.
Network virtualization decouples and isolates virtual networks from the underlying network hardware just like server virtualization decouples and isolates virtual machines from the underlying server hardware. Once virtualized, the physical network is only used for packet forwarding, which allows it to be treated as an IP backplane. Virtual networks are also programmable. Companies such as Nicira and Extreme Networks market virtualized network products: Nicira specializes in open source software for network virtualization and Extreme promotes an intelligent switching architecture.
Recently, VMware bought Nicira, which indicates that VMware is looking to apply virtualization to networking as well as data centers, where they are a major player. VMware acquired the networking part of the virtualization stack. VMware is owned by EMC, who focus on virtualizing storage. Put all the pieces together and you get an interesting value proposition.
Extreme's Doug Wills: "We're seeing similar advances in network virtualization that we saw in server virtualization ten years ago. VMware's acquisition will trigger similar investments and M&A activity around SDN and OpenFlow in the next 12-18 months. It validates the importance of data center automation and network virtualization."
In a somewhat simplistic nutshell, what OpenFlow brings to programmable virtualized networks is the ability to employ Ethernet switches, which are a relatively low-cost commodity product--at least compared to those monolithic boxes. And implementing this protocol standard leads to programmable network applications that can be managed as single virtual machines inside a data center. This means that international mobility will include moving subscriber profiles between data centers. Therefore apps will be synchronized with whatever devices users are employing at that time.
Looking Ahead
SDN is a game-changing development, but it should be seen in conjunction with two other developments: virtualized clouds and virtualized networks. Taken together, they form a disruptive technology triad that is set to turn wide area networking in an open systems environment. Extreme is looking to kick-start this process by implementing OpenFlow and OpenStack across the product line. In addition, the company is giving customers the tools to program their networks and to employ software applications developed in-house or by third parties. The tools include API scripts and free applications that are hosted on an SDN community portal and that can be shared. These developments look set to be part of an industry-wide initiative managed by organizations such as the Open Networking Foundation.
SDN Summary
Enterprises are employing virtual pools of computing resources that operate very efficiently in private and public clouds. IT is in control of these resources, but when it comes to the Internet they get what they get: An infrastructure based on proprietary, monolithic routers and switches.
In a software-defined network these mainframe-type boxes are replaced with regular Ethernet switches, which are much simpler, packet-forwarding devices. OpenFlow is a relatively new protocol designed to control flow tables in these switches. The critical function is the separation of control from forwarding.
An OpenFlow controller can manage a distributed set of network switches as a single virtual switch. Most OpenFlow controllers expose an API to applications. Together the controller and apps behave as a unified Network OS, which allows a network operator to implement an SDN. This is a groundbreaking development: the key that unlocks the potential of SDN and that puts IT in control of the wide area network.
OpenStack is an open source cloud operating system. It controls large pools of computing, storage, and networking resources throughout a data center. Everything is managed through a dashboard that gives administrators control, while empowering their users to provision resources through a Web interface.
