Cable Weighs Ways to Go Virtual
With their access networks facing swiftly growing bandwidth challenges over the next few years, cable technologists are increasingly looking to virtualization to save the day.
From CableLabs to MSO and vendor labs throughout the world, industry engineers are particularly exploring a number of approaches for virtualizing key equipment and network functions now lodged in the cable headend. The various distributed access architecture approaches (DAA) range from moving parts of the cable modem termination system (CMTS) and edgeQAM modulator or Converged Cable Access Platform (CCAP) device from the headend to the network edge to virtualizing all of them and completely eliminating the physical CCAP platform.
In a recent webinar, "The Economic Benefits of Virtualizing the Cable Edge," hosted by Light Reading and attracting one of the largest audiences yet for a cable technology topic, senior technologists from Comcast Corp. (Nasdaq: CMCSA, CMCSK), Liberty Global Inc. (Nasdaq: LBTY), Juniper Networks Inc. (NYSE: JNPR) and Gainspeed discussed the daunting bandwidth challenges that cable operators face and the pros and cons of the various virtualization options. In particular, they focused on DAA and the role that SDN and NFV technologies could play in fostering those architectures.
Both of the major cable operators addressed the explosion in bandwidth demand that their companies face. Rob Howald, VP of Network Architecture for Comcast, said North American cable operators are facing growth in bandwidth demand from a number of sources, including streaming video content from Netflix Inc. (Nasdaq: NFLX) and other over-the-top (OTT) video services, business services, cloud-based video services and such new broadband services as home automation and security, He also cited online gaming and new video technologies like 4K TV.
Phil Oakley, head of access & edge architectures for Liberty Global, said the large international MSO is "seeing very similar dynamics in the European market." For example, he said, with the recent launch of Netflix in a number of European markets, Liberty Global has seen bandwidth demand surge "as high as 20% in some of our regions."
Howald said Comcast has managed to keep up with increases in bandwidth demand so far by boosting data speeds 13 times over the past dozen years and pulling fiber deeper into its network, thereby reducing the size of its service groups connected to each fiber node. But he said Comcast can't keep doing that indefinitely because of multiple factors including: the limited availability of fiber and wavelengths to keep splitting node size, the expense of pulling new fiber, the facilities demands of new equipment, the power and cooling demands and the need for more spectrum.
Yet both he and Oakley insisted that cable's hybrid fiber-coaxial (HFC) networks are still well placed to compete against both telco twisted-pair and fiber-to-the-premises (FTTP) architectures. With the pending launch of DOCSIS 3.1, Howald said, cable operators will be able to offer gigabit speeds to subscribers "much more cost effectively, ubiquitously and faster" than FTTP networks. Oakley agreed, noting that Liberty Global still sees great promise in HFC networks and DOCSIS technology and plans to install all-fiber networks only as a complement to its main HFC strategy.
Samir Parikh, director of product management for Gainspeed, said cable operators are starting to explore the concept of "Distributed CCAP," which calls for moving part or all of the CCAP functions from the cable headend to the network node through virtualization. CCAP itself is a next-gen technology that combines the data processing functions of the CMTS and the video processing functions of the edge QAM in a single device, saving power, space and costs.
Parikh contended that Distributed CCAP, which is also sometimes called Distributed Access Architectures, builds on CCAP's benefits by leveraging "digital transport" to simplify the access network and increase its scale by 10 times or more. "It alleviates power, cooling and space challenges in the MSO facilities," he said. But he noted that "there are multiple flavors of this idea and not all of them are created equal."
Howald said Comcast executives find the notion of D-CCAP very appealing. His company's engineers are now considering DAA because "because of their potential to deliver some important benefits to Comcast that ultimately will allow us to deliver better services to our customers." Those benefits, he said, include greater fiber efficiency through the replacement of analog transport with digital transport, better RF performance through the move of RF signal generation closer to the customer and greater facility scaling through the reduction or elimination of large CCAP or CMTS chassis in the cable headend.
Juniper and Gainspeed, which co-sponsored the webinar, are both strong proponents of the "Virtual CCAP" approach, which would shift all CCAP or CMTS and edge QAM functions out of the headend by eliminating all the physical platforms in the headend and splitting the various functions of the devices between the existing router in the headend, the network node and the cloud. They argue that this approach, as opposed to such other emerging options as Remote PHY and Remote MAC that would move just some of the CCAP functions out of the headend, provides the greatest benefits, especially large space, power and capex savings.
Seeking to buttress their case, Parikh and Andrew Smith, chief architect of cable MSO networks for Juniper, also maintained during the webinar that Virtual CCAP leverage both SDN and NFV technologies to achieve greater operational efficiencies. As a result, they said, V-CCAP produces greater economic benefits than the other methods. "Virtual CCAP leverages both SDN and NFV technologies to transform CCAP," Smith said.
With CableLabs now developing interface specs for Remote PHY and investigating the other options as well, neither Comcast nor Liberty Global has yet committed to any of the DAA approaches. But both Oakley and Howald said their companies are closely examining the different options as they prepare to roll out DOCSIS 3.1 and other advanced services.
— Alan Breznick, Cable/Video Practice Leader, Light Reading