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The Link Between Software-Defined Networking and Passive Optical LANs

The Link Between Software-Defined Networking and Passive Optical LANs

We’ve previously outlined some of the major benefits of installing a passive optical network for your company’s technology infrastructure. Recent industry news and research has reinforced some of these benefits and has some speculating on future developments for passive optical LANs.

The Development of Service Providers’ Networks May Suggest Future Developments in Enterprise LAN Environments

Passive optical local area networks (passive optical LANs) are a technology that was developed for fiber-to-the-home/fiber-to-the-X networks. This type of network is now making its way into the enterprise, making it a key example of technologies that are expanding/shifting to the enterprise in this way. Organizations and groups—notably including the Association for Passive Optical LAN (APOLAN)—have emphasized for several years that passive optical LANs incorporate proven technologies that have served FTTx networks for years.

In a white paper titled “Smarter Networks with Passive Optical LANs,” experts from IBM open with this: “In the 1980s and 1990s, optical communications revolutionized long-haul transmission. Today, the long distance and underwater communications are the backbone of every major provider consisting of optical fiber. The technology has shown to be vastly superior to copper in terms of bandwidth, range, consumed power, longevity and reliability. Recent advances in the manufacturing and commercialization of passive optical components are now extending these capabilities to the edge and campus networks. Buildings that have been traditionally wired with Cat 5/6 copper are facing fantastic opportunity from the emergence of passive optical LAN technology…”

Given the degree that passive optical networking technology now has been adopted in enterprises, the technological evolution currently occurring in service-provider networks could be an antecedent to eventual developments in enterprise environments.


On October 5, AT&T Labs’ associate vice president for technical design and architecture, Eddy Barker, revealed in a blog post that AT&T released the Virtual Optical Line Termination Hardware Abstraction (VOLTHA) into the Open Networking Foundation. Baker wrote: “This is the first major open-source software release that provides the ‘brain’ for XGS-PON technology. It also delivers on our commitment to move toward open source software and SDN/NFV [network function virtualization] frameworks.”

Barker went on to describe XGS-PON as a passive optical network that promises “broadband connectivity up to 10 Gbits/sec. XGS-PON is a fixed wavelength symmetrical 10-Gbit/sec passive optical network technology. It can coexist with the current-generation GPON [Gigabit Passive Optical Network] technology and provide 4x faster downstream bandwidth. It’s as cost-effective as GPON.”

The Open Networking Foundation defines itself as “a non-profit operator-led consortium driving transformation of network infrastructure and carrier business models … The ONF serves as the umbrella for a number of projects building solutions by leveraging network disaggregation, white box economics, open source software and software defined standards to revolutionize the carrier industry.”

One of the ONF’s projects is CORD—Central Office Rearchitected as a Datacenter. “The edge of the operator network (such as the central office for telcos and the headend for cable operators) is where operators connect to their customers,” the ONF says. “CORD is a project intent on transforming this edge into an agile service delivery platform enabling the operator to deliver the best end-user experience along with innovative next-generation services.”

“The CORD platform leverages SDN, NFV and cloud technologies to build agile data centers for the network edge.,” ONF continued. “Integrating multiple open source projects, CORD delivers a cloud-native, open, programmable, agile platform for network operators to create innovative services.”

CORD is packaged into three solutions for different market-use cases, ONF explained. M-CORD supports 5G mobile edge services with disaggregated and virtualized radio, and an open source mobile core. R-CORD supports residential subscribers over wireline access technologies like GPON,, 10GPON and DOCSIS. E-CORD supports enterprise services such as virtual private networks and application optimization (software-defined WAN) over metro and wide area networks.

The VOLTHA 1.0 release is a notable milestone for the CORD project. AT&T’s Barker stated that major software releases like it “are necessary to fulfill our vision of a software-defined network, which employs NFV. We expect to have 55 percent of our networks virtualized by the end of 2017. We aim to have 75 percent of our traffic on our software-defined network by 2020, and we’re pushing hard to beat that goal.

“Open software efforts benefit the industry because we rely on the active participation and feedback form a large community of developers,” he added. “Developers can improve, add, and influence changes to the software that will help us deliver XGS-PON technology to customers quickly. We are currently performing proof-of-concept testing of VOLTHA in our labs and are planning to deploy XGS-PON field trials before the end of 2017.”


Most likely, it will be quite a long time before something resembling VOLTHA emerges in mainstream enterprise networking. However, SDN is a timely topic for the LAN. In a document intended for federal-government users, Tellabs states that passive optical LAN offers the best architecture for software-defined LANs. The document describes that as government network administrators assess the advantages and merits of SDN functionality in buildings and across campuses, they are doing so “under the assumption that SDN fixes traditional LAN operational efficiencies, security and reliability shortcomings. However, what they don’t realize is that by bolting-on SDN as an overlay to a legacy LAN design, they leave the inherent weakness of traditional LANs.”

Tellabs further contends, “Adding complexity with SDN can marginally improve LAN operational efficiencies, security and reliability, but by introducing more sophistication, the fixes can negatively contribute to the same attributes they were intended to repair. Furthermore, there are alternative means of addressing the underlying fundamental faults relative to traditional LAN … that specifically fix root problems.”

Tellabs explains that passive optical LAN is an example of alternative means. They articulate the potential drawbacks of implementing SDN as an overlay to a traditional LAN:

  • Access, aggregation, distribution, and work-group switches are complex, full-functioning devices, representing potential security weaknesses.
  • Complex full-functioning switches spread across buildings and a campus equals distributed intelligence and management at each port, thereby requiring local provisioning, troubleshooting and management of higher-level IP and Layer 3 functions at each port.
  • Adding SDN protocols to existing full-functioning switches inserts security, operation, and reliability complexities.

On the other hand, Tellabs argues that an optical LAN “marries the best features of passive optical networking with advanced Ethernet functionality. It does so within the framework that matches cloud, wireless, hosted/managed services, data center and SDN architecture—all of which have the common trait of having centralized intelligence and management.” Additionally, a passive optical LAN can define network resources in software and dynamically allocate them based on real-time demands.

Tellabs underscores this: passive optical LAN facilitates SDN implementation in part because “simple unmanaged ONTs [optical network terminals] are better suited for SDN rather than complex full-functioning traditional switches,” and because a passive optical LAN “will allow a mixture of G-PON, XGS-PON, and NG-PON2 [40G] technology choices simultaneously, without the rip-and-replace of today’s infrastructure.”

As IBM’s white paper pointed out, optics changed service-provider networks in the 1980s. It was around 2010 when passive optical LAN technology took hold in enterprise networks. It may be decades before the fruits of the ONF’s efforts are enjoyed by enterprise networks—if they ever are. However, advocates of passive optical LANs are looking to and citing history to make their claim for what’s in store in the future.

Interested in Passive Optical LAN for Your Southwest Business?

With the many advantages of passive optic LAN, it may be the right choice for your business. But that decision is best made when consulting with a professional. Corporate Technology Solutions has been providing turnkey low voltage and structured cabling solutions throughout the Southwest for over 15 years. We have offices in Tempe, Tucson and Las Vegas and would be happy to discuss your business’s needs and technology strategies. Contact us online or give us a call today.

This entry was posted on Friday, December 22nd, 2017 at 1:29 pm and is filed under Blog. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

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