Comcast said it achieved speeds of 8.5 Gbps downstream and 6 Gbps upstream on a live network using several elements of the cable industry 10G standard, including DOCSIS 4.0. It’s important news, considering that until now cable companies have generally only deployed 10G technology in a lab environment.
The Cablelabs 10G initiative includes several elements aimed at boosting the bandwidth that cable companies can support using their existing hybrid fiber coax (HFC) network infrastructure. The standard also encompasses other goals such as reducing latency and improving reliability.
The standard calls for speeds up to 10 Gbps downstream and 6 Gbps upstream. Cable companies can implement various elements of the standard separately or together to obtain incremental speed boosts toward those goals.
10G Technology Elements
Among the elements included in the 10G standard are DOCSIS 4.0, a distributed access architecture (DAA) that uses software defined networking (SDN), decentralizing the cable modem termination system (CMTS) and opening up more frequencies within the coaxial connection for upstream traffic using what the cable industry calls a full-duplex approach. Cable companies also may need to split nodes or take fiber deeper into the network to maximize speeds.
The Comcast live network trial used several elements of the 10G standard, as the company describes in a press release.
“For the demo, Comcast connected a 10G-enabled Virtualized Cable Modem Termination System (vCMTS) linked by more than 80 kilometers of fiber to the demonstration site,” Comcast explained. “The fiber terminated into a production switch, which connected to what is believed to be the world’s first fully functional 10G-enabled Full Duplex DOCSIS 4.0 node, along with a 10G prototype modem at CableLabs headquarters.”
The demonstration was “orchestrated” by DAA technology that, according to Comcast, has already been widely deployed in the company’s network. Comcast expects 10G and DAA technology to provide greater reliability by providing greater visibility into network performance.
Adding PON
According to Comcast, the demo also showed how a single DAA-enabled vCMTS can simultaneously operate both 10G connections and passive optical network (PON) connections. This could prove to allow Comcast to mix and match cable 10G and fiber optic technology as needed.
“While Comcast is primarily focused on 10G, the ability to easily blend 10G and PON provides enormous flexibility to support the widest range of geographies and customer needs,” a press release notes.
Cable companies are working hard to determine their best path to upgrade their networks to support faster speeds. They are particularly interested in boosting upstream speeds, which have been the most limited. Faster upstream speeds have become increasingly important as consumers demand greater symmetrical bandwidth to support applications such as videoconferencing.
In January, Comcast achieved symmetrical speeds of 4 Gbps bi-directionally in a lab trial using DOCSIS 4.0.
The same month, Charter demonstrated speeds similar to those that Comcast cited yesterday (8.5 Gbps downstream and 6 Gbps upstream), also in a laboratory trial.
