Virtualization: Building specs for remote MACPHY

April 17, 2018
CableLabs recently launched the Remote MACPHY working group as part of its Distributed CCAP Architecture program in order to develop specifications to ensure the interoperability of MACPHY solutions when ...

CableLabs recently launched the Remote MACPHY working group as part of its Distributed CCAP Architecture program in order to develop specifications to ensure the interoperability of MACPHY solutions when deployed.

As the name indicates, the aim of remote MACPHY is to put both main functions of the CMTS/CCAP device - the MAC and the PHY - out into the access network. "Technically speaking, you (wouldn't) have anything in the headend that would resemble a CCAP any more," said Jon Schnoor, lead engineer, CableLabs wired technologies.

The first phase of the MACPHY project will see the MAC and the PHY in the node together as kind of a mini-CMTS self-contained in the node. Then in phase 2, the MAC and the PHY will be pulled apart again. The remote MAC core will be MAC functionality in software form, which could be installed anywhere in the access network - headend on a shelf, hub site, in a pedestal, etc.

"It gives operators flexibility," Schnoor said.

Phase 1 provides the shortest path to market, with the MAC and PHY together in the node. With this scenario, there are fewer interfaces than if the components were separate and will allow interoperability testing to begin sooner, Schnoor said. Each phase builds on what came before so that when the MAC is pulled out again, the functionality of the components is already there.

The timeline is still being defined within the Remote MACPHY group. Right now, the discussion is centering on what the interfaces are that need specifications. Phase 1 should be well underway by the middle of the year.

"The plan is to hit major milestones each quarter so that in 2019, operators can hit the ground running with certain features," Schnoor said.

As for the benefits, aside from flexibility, distributed access and remote MACPHY bring the ability to provide the gigabit speeds users are demanding without the real estate and power requirements.

"Operators want to get out of the real estate business … to build out the infrastructure to support bandwidth needs (without a distributed architecture), they would have to double or triple their real estate. They don't want to do that," Schnoor said.

Remote MACPHY architecture also will allow operators to remove or replace analog optics in the access network with digital optics to extend the reach of the access and reduce costs. Ethernet can be used between the CCAP core and the PHY device, which removes the constraints of traditional cable and analog optics. Fiber amplifiers are not needed, and operators can increase access network distances and get better efficiency, Schnoor said.