Q&A: Learning More about CableLabs® New Coherent Optical Specification
CableLabs recently released a specification for coherent optics that is a significant development to support Distributed Access Architectures (DAA) and MSO access networks, we sit down with Ciena’s Eric Maniloff and Chris Gosnell to learn more.
On June 29th, CableLabs publicly unveiled two new specifications for the cable market, they are the P2P Coherent Optics Architecture Specification and the P2P Coherent Optics Physical Layer v1.0 Specification (“P2P” stands for Point to Point in this instance). CableLabs said that these two new specifications are the result of a focused effort by CableLabs, their members, and manufacturer partners to develop Coherent Optics technology for the access network and bring it to market quickly.
Matt Schmitt, the chair of the CableLabs Coherent Optics Project said, “These specifications represent the beginning of a sea change for the way data is distributed into the network by greatly expanding the capacity of existing cable operator fiber access networks, while meeting ever-increasing capacity demands at the lowest possible cost.”
Eric Maniloff, Systems Architect, and Chris Gosnell, Senior Manager – Field Systems Engineering, from Ciena are both active participants in the CableLabs Coherent Optics Project, so we sat down with them to learn more about this work, what it means for the cable industry, and of course – what’s next.
- To get started, can you provide a general overview on the work CableLabs is doing and the recent specifications that were announced?
Chris Gosnell: Distributed Access Architecture, combined with a push toward Fiber Deep, is an emerging re-architecture of cable networks to provide 1Gb and higher data rates to cable customers. The new architecture will create a massive increase in the amount of bandwidth travelling through cable providers’ networks. Of particular concern is the fiber link between the head-ends and the remote nodes, as this is a tightly constrained section of the network making it one of the most difficult and costly to upgrade.
Eric Maniloff: CableLabs has identified coherent optics as a way to aggregate and transport that additional bandwidth, as it has demonstrated a ten-fold increase in the capacity of existing cable access plant, with even more improvements possible. The specification that CableLabs has recently published will enable vendors to build products to a common interoperable specification to support this increased capacity needed for DAA and Fiber Deep. - So, what does this mean for the cable industry?
Eric: CableLabs’ coherent optics specification will enable interoperability between vendors at either end of the fiber link. This means that MSOs will now be able to select different vendors that are optimized for the specific applications at the remote node and the headend. This follows in the footsteps of CableLabs’ DOCSIS specification which introduced interoperability to the cable data layer.
Chris: The specifications that CableLabs produced are optimized for the access application where distances are relatively short, environmental conditions are harsh, cost requirements are stringent, and the coherent signal will need to coexist with existing analog QAM and 10Gb/s Ethernet signals on the same fiber. Another challenge the specifications will help with is the need for the remote side of the optical link to be placed on outside cable strands or street level cabinets, with temperature ranges across the North American MSOs ranging from -40°C in the frozen North to +70°C in the southern deserts! - How is this advancing the cable industry?
Eric: Currently the highest digital optical connection rate used in this application is 10 Gb/s per channel. The initial coherent specification interoperates with the existing optical fiber channel plan and increases each optical channel to 100Gb/s, enabling MSO’s to scale the existing optical infrastructure 10x. Coherent optical transmission will scale to even higher capacities in the future. The 100G specification allows a direct overlay on existing optical links, as defined by the specification.
Chris: Additionally, by having the MSOs commit to this standard specification for coherent optics in the cable access network, it will drive an increase in more open solutions that can interoperate at either end of the fiber link.
Eric: The new 100G coherent specification allows cable operators to seamlessly work with existing optical infrastructure, enabling digital transformation of the headend, hub and remote node; provide scale; and improve quality of customer experience with new services. - When do you think we will see these developments in actual networks?
Chris: Distributed access architecture was deployed sparingly in 2018 with accelerated deployments in 2019, which will start to strain the access bandwidth capabilities. The members of the CableLabs Coherent Optical Project expect to see compliant coherent optics devices available for some applications in 2019. - Why has Ciena been involved in this work?
Eric: Ciena is actively involved in all major standards bodies associated with networking. We use our experience to help define specifications and ensuring our products are designed to be standards-compliant to enable interoperable networks.
Chris: As I discussed above, the access networks that the coherent specifications are being designed for have some unique features. As pioneers of coherent optical technology, we were able to bring our wealth of experience in terms of analyzing different optical applications to the table.
Eric: We are also heavily involved in developing coherent specifications in other Multi-Source Agreements such as OpenROADM, and standards bodies such as the ITU and OIF, so we are helping to ensure that the CableLabs specification aligns with other bodies where possible, while at the same time making sure that it addresses the specific requirements for MSO networks. - What is next?
Chris: The work does not end here! Even before the final publication of the 100G specification, the Coherent Optics Project had started work on a 200G specification, with higher speeds on the horizon.
Eric: Work is ongoing on the specification of a management interface to the coherent optics specifications, as well as methods to test devices to ensure compliance with the specification.
If you would like to learn more about this work from the CableLabs organization, check out their article here.
