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Going the virtual CMTS route

Despite a slow start, cable operators are increasingly moving to virtualize their hybrid fiber-coax (HFC) access networks as the next-gen technology emerges as critical to the industry's long-term health and competitive prospects.

The many benefits of vCMTS

That's because virtualized cable modem termination system (vCMTS) technology, which takes key access network functions out of the traditional cable headend and places them in software running on commercial off-the-shelf servers (COTS), promises many benefits for operators as they look to meet the capacity and connectivity challenges of a new decade. Such benefits include increased network capacity, better signal quality, fewer hub sites, reduced power and cooling requirements, easier plant maintenance and lower overall operating costs.

Further, vCMTS technology enables cable operators to shift to a distributed access architecture (DAA) by disaggregating the CMTS. In turn, this allows operators to move to IP-based connectivity and converge their voice and data services with their video and other legacy services. This shift can make it easier and faster for them to boost upstream capacity without having to grapple with the splitters and combiners normally associated with node splits. It also means that operators no longer need to manage and maintain traditional, bulky CMTS gear.

Moreover, the new virtualized infrastructure gives operators the power to gather real-time data and perform analytics, enabling them to pinpoint and fix problems quickly. As a result, cablecos can keep outages contained to extremely small segments of their customer base.

For instance, Comcast, an early adopter of vCMTS technology, estimates that its new distributed/ virtualized access network/ architecture can limit its failure points to no more than just a single fiber deep node, or about 40 customers. That stands in stark contrast to a legacy cable hub site of 20,000 to 30,000 customers using a traditional CMTS.

Combined with a complementary DAA strategy, a vCMTS approach should enable cable providers to compete better with rival wireline providers deploying all-fiber networks, as well as wireless providers rolling out 5G mobile technology. Such a combination could also permit cable providers to expand beyond their traditional DOCSIS and CMTS platforms and take greater advantage of passive optical networking (PON) technology and optical line terminal (OLT) equipment.

Strong early interest but major challenges

Small wonder, then, that Harmonic is seeing strong early interest in its CableOS solution for virtualized cable networks and distributed access deployments, as indicated in several articles in this e-book. At the end of Q3 2020, the vendor reported 38 commercially deployed customers for CableOS globally, up 100% from the year-ago period. Those deployments covered about 2.1 million served cable modems, up 122% from the year before.

Of course, like any new technological initiative, virtualized access networks also present some major new challenges for the cable industry. Chief among them is the enormous operational challenge of making the complex conversion from purpose-built CMTS hardware housed in a plethora of headends and hubs to a cloud-based software infrastructure managed from a much smaller number of advanced data centers.

In an interview with Light Reading at SCTE Cable-Tec Expo in New Orleans last year, Tony Werner, Comcast's president of Technology, Product and Xperience, noted that it's "a big change to go from CMTS appliances to all of the sudden a cloud-based architecture with COTS hardware and running Kubernetes and powering this from a few data centers versus having CMTSs out deep in the hubs and the headends."

Other key challenges include maintaining the performance, reliability, resilience and redundancy of the cable access network while making that conversion and then scaling the new virtualized architecture. That's a big reason why cable operators have moved slowly and cautiously to carry out the required changes until recently.

An examination of advances and challenges

This e-book highlights some of the early advances made by Harmonic and its cable customers of all sizes including Comcast, Buckeye, Comporium, Westman Communications and 1Tennessee in virtualizing their cable access networks and expanding their capacity. In addition, the e-book examines the opportunities and challenges that vCMTS technology is bringing to the cable industry. It also delves into the progress that service providers are achieving with related next-gen technologies such as automation and artificial intelligence.

For a free download of the new e-book, please click here click here to get your copy.

— Alan Breznick, Cable/Video Practice Leader, Light Reading


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