No Easy Path: Operators Grapple with SDNs

June 4, 2014
Software-defined networks (SDNs) completely reimagine the approach to networking in data centers and telecommunications networks of all ...
Software-defined networks (SDNs) completely reimagine the approach to networking in data centers and telecommunications networks of all sorts. Indeed, it is difficult to overestimate the impact that they will have.

But the changes are coming, and the market is expected to grow rapidly. Grand View Research says that the market will expand from $326.5 million last year to $4.9 billion in 2020, which is a compound annual growth rate (CAGR) of 44.2 percent (starting this year).

The growth will not be linear, however. Infonetics Research has identified what it calls “SDN hesitation.” The firm says that current infrastructure is being “nursed along” until the myriad complexities of the revolutionary networking scheme are worked out. That has led to a lull in sales as carriers bide their time and avoid investments in older approaches.

Where does the cable industry fit into this mosaic? Though MSOs haven’t been in the forefront of SDN developments, the cable industry certainly stands to be one of the biggest users of the technique. Benu Vice President of Marketing Troy Dixler suggested that the use of SDNs by cable operators will be fundamentally different than the earlier adopting telephone operators and data centers segments.

The focus the MSO community now is on building out the highly specific use cases that are more appropriate for cable, he said. Benu is funded by Spark Capital, Sutter Hill Ventures, Comcast Ventures and ARRIS. It has deployed a footprint-wide community WiFi overlay with an unidentified cable operator, though Dixler said that the initiative doesn’t use SDNs.

SDN essentially divide and conquer. What they divide is the data that is being transported from the layer of intelligence that maps out the trip. What this conquers is inefficiency. Networks can be reconfigured far more quickly, with less labor and in a manner that takes the big picture into account. A third layer carriers the applications - streaming video, voice services and all the others - that the service provider will offer. (A related new technique, network functions virtualization, is the creation of software-based network elements, such as set-top boxes and firewalls.)

Dixler said that the work on OpenFlow, an emerging set of open SDN specifications being created by the Open Networking Foundation, has to date focused on integration in the “southbound” direction - from the control to data planes. Cable operators, Dixler said, have a far wider array of use cases than a data center. For that reason, they are more actively pushing the enfranchisement of “northbound” integration of the control plane up to application layers. The ONF, Dixler said, “now is actively trying to standardize the northbound” interfaces.

Chris Donley, CableLabs director of advanced networks and applications, said that the industry is well-positioned to integrate SDNs. The creation of applications, he said, can be done via cable specifications that are supported by the Open Networking Foundation: Netconf with Yang modules and Packet Cable Multimedia (PCMM). These, he said, can facilitate applications that fit the industry’s use cases.

The cable industry’s rampup to SDNs will be challenging for a three reasons, said Adam Dunstan, the CEO of Active Broadband. It is in the cable industry’s DNA to upgrade and advance its technology. Therefore, there is less of a compelling need to take the huge leap the switch to SDNs represents. The telephone companies, conversely, rely on technologies that are a bit longer in the tooth and may be more amenable to taking the radical step, Dunstan said.

The functions that would be most impacted by a move to SDNs are concentrated in the CMTS while, in the telephone industry, they are naturally separated between optical line termination and broadband network gateway (BNG) devices. Thus, the changeover can be done more gradually in the telco world. Finally, Dunstan said, tasks such as OSS and networking are carried out by a unitary structure in most data center environments. Tasks are decentralized in the cable environment. This makes a coordinated transition to a completely new approach more difficult.

Donley said that CableLabs is working with its members to virtualize CCAP and CMTSs. An overall architecture has been set. The details remain to be hashed out. “We’ve reached agreement on the pictures,” Donley said. “Now we have to get all the wording correct.”

The real action will start when it truly becomes apparent that SDNs perform better and are more economical. “It’s interesting to talk about SDNs, but until someone comes in and [demonstrates that] they have better a mousetrap and one that’s cheaper, it’s just talk,” he said. “Some things will be virtualized, but they will be bits and pieces that they call SDNs.”