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Is the optical domain ready for SDN?

Don Frey, Principal Analyst, Transport and Routing

Transport SDN (software-defined networking) promises to be the glue that will hold disaggregated optical networks together, in addition to enabling carriers to realize additional revenue from their already deployed systems. There have been multiple discussions at OFC around the use cases and challenges to deploying SDN.

During an OFC panel on Monday, carriers explained their respective and different applications based on optical plus Layer 3, management across vendor domains, or disaggregated ROADM applications. All four carriers on the panel are trying to solve different problems through their use of SDN. Telefonica hopes that SDN can solve the OSS/BSS bottleneck, which delays the adoption of new optical technology. In its use of SDN, AT&T has been focused on reducing wavelength-provisioning times, while NTT pursues ONOS (Open Network Operating System)–based orchestration of Layer 2 and optical.

Carriers face numerous challenges because vendor solutions implement functionalities differently. Additional integration work is often required, especially when a carrier goes from one vendor domain to another. On Tuesday, the OIF announced that it will start work on SDN Transport API 2.0 to address the gaps in vendor implementations. Currently, SDN control for optical is best done using solutions from one vendor; otherwise, a carrier will have to pay for integration across multiple vendor domains.

Carriers differ on their view of the white box

Don Frey, Principal Analyst, Transport and Routing

The optical white box came into vogue a few years ago with the introduction of the optical data center interconnect blade. This week at OFC, service providers shared their latest views on what the "white box" means to them and the ecosystem.

Not surprisingly, each type of carrier was focused on different applications. Telecom carriers focused on two deployment options: fully integrated systems to address complex legacy problems, or a completely open system based on the Open ROADM, to allow for better flexibility than is available on the legacy network. Web-scale operators are creating optical blades that address individual problems, but that address fewer applications for other operators. Lastly, data center operators are addressing metro and regional networks because they believe problems are easier to fix in these portions of the network. Additionally, the data center operators will not require interoperability between vendors.

Carriers have a plethora of choices beyond integrated products. This OFC panel discussion made it clear that many carriers are deploying purpose-built products for select problems to gain experience with disaggregation without pursuing the larger model. A smaller set of carriers is beginning to deploy Open ROADM without pursuing vendor interoperability. As the technology matures and providers gain experience, we expect that adoption of disaggregated solutions will grow.

Service providers want openness in optical wireline access, even though the definition of openness varies widely

Julie Kunstler, Principal Analyst, Components and Next-Gen Infrastructure

Service providers are striving for openness in their optical wireline access networks but there is no consensus on the definition of openness. During Wednesday's "Network Operator Summit" panel, four service providers (AT&T, Comcast, NTT, and China Telecom) presented their respective next-gen optical access plans. For China Telecom, openness evolves around equipment interoperability, namely, the ability to mix and match OLTs from one vendor with ONT CPEs from another. This type of openness supports operational flexibilities such as the ability to replace a customer's ONT without the need to check which vendor's OLT port is connected to that particular customer. This mix-and-match approach may also lead to lower equipment costs because China Telecom can issue separate RFPs for OLT and ONT equipment.

AT&T's approach encompasses ECOMP, its framework for real-time, policy-driven software automation of network management functions along with its work with ON.Lab (open networking). AT&T has created an open OMCI (ONU management and control interface) to drive interoperability between different vendors' OLTs and ONTs. It plans to submit its OMCI specs to the ON.Lab's forum and through ITU FSAN. Virtualization of central-office functions extends to OLTs through the vOLT approach. A vOLT replaces proprietary OLT equipment with a combination of open source software and commodity hardware.

While the definition of openness varies from operator to operator, there is commonality in the push toward reducing vendor tie-in.



Julie Kunstler, Principal Analyst, Components, Next-Gen Infrastructure

Don Frey, Principal Analyst, Transport and Routing

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