Comcast Cable EVP and Chief Network Operator Elad Nafshi brushed aside speculation that the number of DOCSIS 4.0 pathways available to operators could slow rollouts, arguing such flexibility is a boon rather than a burden for cable companies.
Speaking during Fierce’s Broadband Technology Summit, Nafshi said the optionality DOCSIS 4.0 offers is one of its key strengths.
“I think that if DOCSIS 4.0 were a one size fits all, because of the nature of the implementation, it would actually greatly limit the adaptability and acceptance of DOCSIS 4.0 within the operators,” he said. “We each have our own networks, we each have our own network realities, we each have our own distribution of set top boxes and CPE devices and geography, reach and so on and so forth…I think that the optionality gives us more footprint to cover as an industry.”
He explained Comcast landed on the Full Duplex (FDX) version of DOCSIS 4.0 as opposed to the Extended Spectrum (ESD) model because the operator felt it was the right fit to meet the needs of its customers, CPE mix and network overall. But that doesn’t mean other operators can’t or won’t pursue ESD.
Nafshi also addressed the rationale behind Comcast’s decision to pursue Remote-PHY, one of two key models for distributed access architecture (DAA). Remote-PHY calls for DOCSIS computing to be done at the headend, whereas the other DAA option, Remote-MAC PHY, pushes it out to the node. To date, he said Comcast has deployed more than 30,000 Remote-PHY nodes.
“The decision of where to put processing is as old as computing. It’s really around how do you optimize for the computing power based on location and the constraint of that location,” Nafshi said. He argued the hardening needed to put computing at the node comes “with a lot of cost ramifications,” while the latency benefits of running compute closer to the edge of the network with Remote-MAC PHY are minimal and “easily bridgeable with system optimization.”
By running its compute at the headend with Remote-PHY, Nafshi said Comcast is able to essentially rely on webscale speeds and run a data center-type of computing that “following Moore’s law will become twice as capable at the same cost every 18 months.” So, for instance, he noted Comcast has already achieved a 20:1 rack reduction over older generation CMTS technology and by the end of the year “that density will double by transitioning over to the next generation of Intel servers and two years from now it will double again.”
But again, he said that doesn’t mean Remote-MAC PHY won’t be the right choice for another operator’s needs.
During the session, Nafshi also touched on the importance of amplifiers to its DOCSIS 4.0 plans and chimed in on the debate over whether fiber is the logical end state of coaxial networks. Catch a replay of the session by registering here.