OLTs are the last frontier for network disaggregation

  • Broadband Forum released new standards for disaggregating network OLTs

  • They argued disaggregation can help lower costs and simplify network management

  • Adoption could take some time, Dell'Oro's Jeff Heynen said

Just like the Oregon Trail, the process of disaggregating the network has been a long and arduous journey. But there’s finally an end of sorts in sight as Broadband Forum tackles the final peak standing between operators and full disaggregation: optical line terminals (OLTs).

Earlier this month the group unleashed its TR-477 and MR-477 standards, which provide a migration path from traditional access nodes to disaggregated ones, with a specific focus on OLTs.

Wait, disaggra-WHAT? Basically, Broadband Forum has created a way for operators to decouple the hardware from the software in access nodes. So, rather than the software living in the node, it can now reside in the cloud. Or part of it can, at least.

This shift means that operators can use white-box hardware at the node, which theoretically opens the door to increased vendor diversity and cost savings. It also enables cloud-based improvements to workflows, automation, update processes and more. That latter bit is all part of Broadband Forum’s idea of a Cloud Central Office (CloudCO).

Bruno Cornaglia, Broadband Forum’s work area head for SDN and NFV, told Fierce Telecom “the OLT is the last portion that needs disaggregating on the network.”

Indeed, we’ve covered efforts to disaggregate the cable modem termination system (CMTS) in the cable realm as well as those to do the same to the broadband network gateway (BNG) in the past. It’s also worth noting here that the Open Networking Foundation has previously taken aim at the OLT issue with its SDN-Enabled Broadband Access and Virtual OLT Hardware Abstraction specs.

Cornaglia said not all access node software is moving to the cloud, but the part related to customer management. You know, the OLT bit.

Broadband Forum CEO Craig Thomas told us that by moving OLT functionality to the cloud, operators can reap capex savings by using white-box hardware and moving to a single management plane and opex savings thanks to simpler management and single service windows.

He added disaggregated OLTs could also come in handy with fiber consolidation on the horizon.

“If new fiber operators are acquired [or] consolidated then disaggregated OLTs with a common CloudCO approach would mean negating the need for rip and replace or managing multiple OSS platforms,” he explained.

Thomas added that the marriage of disaggregated OLTs, a virtualized control plane and fixed access network sharing also gives operators the flexibility to “in effect, network slice their own ports or cards within the OLT for their own services rather than use a wholesale model.”

There can be some downsides to disaggregation, though. For instance, Cornaglia acknowledged that “new operational processes are needed” when software moves to the cloud. That’s a drawback operators have to tackle.


Dell’Oro Group VP Jeff Heynen told Fierce Telecom that some, including Deutsche Telekom (DT), have been dabbling in disaggregation efforts. DT a few years back was working with Radisys and Edgecore on white box OLTs, and those remain the two vendors which would benefit the most if more operators move in this direction.

However, migration efforts could take a while.

“Over time, you will see continued separation of hardware and software, but it is going to take much longer in access networks than it will in routing and subscriber management,” Heynen said. “Access network elements often need to be placed in the edge or outside plant, so there is some reluctance to do full disaggregation when a truck roll might still be required to diagnose and troubleshoot physical layer issues.”

As far as distributed access architecture (DAA) goes, cable players are actually moving faster than other operators when it comes to adoption, he added. They’ve already begun deploying Remote OLTs with separated control and data planes alongside vBNG and vCMTS capabilities.

“We will continue to see that architecture grow as operators add more fiber-based service groups and want to manage their fiber subscribers similarly to their DOCSIS subscribers,” he concluded.