@ The Cable Show: Long live CCAP

Wed, 06/15/2011 - 8:30am
Mike Robuck

The melding of Comcast's Converged Multiservice Access Platform (CMAP) specification with Time Warner Cable's Converged Edge Services Access Router (CESAR) spec into CableLabs' Converged Cable Access Platform (CCAP) specification wasn't a Herculean effort since both devices shared common attributes, but the end result does provide more clarity for vendors and cable operators alike.

Tuesday's session "Space craft: Transforming the headend with CMAP" was CCAP's official debut after CableLabs released its CCAP Architecture Technical Report Tuesday.

“The  effort by the authors of CMAP and CESAR specs to bring the two together was on the order of a few weeks,” said Jeff Finkelstein, Cox Communication’s senior director, network architectures. “There were very few items between CMAP and CESAR for us to discuss.”

CCAP integrates the functions of broadcast and narrowcast quadrature amplitude modulators (QAMs), as well as DOCSIS 3.0 downstream and upstream interfaces. It also includes the option to support passive optical network (PON) termination equipment in the same chassis.

Cable operators are faced with an increasing amount of QAMs taking up more and more rack space, as well as the costs associated with cooling all of those QAMS, as more bandwidth is eaten up by narrowcast services. CCAP also provides a migration roadmap to video over DOCSIS.

"The CMAP and CESAR specifications described the same device with different operational uses," said Jorge Salinger, Comcast's vice president of access architecture. "The resulting CCAP specification provides additional clarity on how the same device can be used in both operational models, while the basic elements of CMAP and CESAR are still in place."

The end result for cable operators is they can now choose to deploy the device as they need to and when they need to.

"One of the key things we have to look at is where we are trying to get to in the long term," Finkelstein said during Tuesday's panel. "As we are moving forward in time for those that have done a modular deployment, we're continuing to deploy the CMTS core kind of functionality to communicate with DEPI (Downstream External PHY Interface) down to the edge QAM. For those that have done the integrated approach, they're getting greater and greater densities."

With CMAP and CESAR now part of CableLabs' interface specs, cable operators will approach CCAP deployments largely based on their current architectures. Cable operators that are using a modular CMTS architecture will likely pursue a modular CCAP approach, while the same should ring true for integrated CMTS architectures.

"To make a radical shift from one to the other is very complex, and not just from an equipment perspective," Finkelstein said. "As we are moving forward to CCAP, to take these incremental steps to get toward an integrated chassis seems to be a logical choice for us. Where we go beyond that, there are still many discussions to be had."

Finkelstein said Cox is looking at having CCAP devices in its labs in late 2012 or early 2013. He said it will be a "lengthy effort" because Cox wants to be methodical with anything that could impact subscribers.

Comcast has aggressively pursued bandwidth reclamation through its all-digital conversion and use of digital terminal adapters. As a result, Comcast will move to CCAP implementations sooner than Time Warner Cable, the latter of which chose to use switched digital video for additional bandwidth.

Over the long haul, Time Warner Cable may decide to use CCAP for its transition to IP video, which would be several years down the road.

Salinger said Comcast is still on track to conduct its CCAP trial later this year, with the first deployment slated for next year.

There are various ways to slice CCAP implementations, including "CCAP lite" that Finkelstein said will increase densities in the short term by collapsing video and data into the same physical ports. CCAP lite could use the deployed technologies with additional CCAP functionalities, such as the combined network and a better management interface to reduce equipment.

With DOCSIS and video QAMs being moved to a single platform, Finkelstein said CCAP devices are very complex and that staging might take place in phases by "eating the elephant one bite at a time."


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