New Standard De-Couples the ONT and OLT in FTTP Broadband

The Broadband Forum has published a new standard that may help to tackle the issue of vendor lock-in on Fibre-to-the-Premises (FTTP) broadband ISP networks, which can result in the management cycle of optical modems (ONU / ONTs) being tied to a specific vendor’s Optical Line Terminal (OLT).

Just to translate this. When you get a FTTP service installed in your home, an engineer will generally fit an Optical Network Terminal (ONT / ONU) on to your wall, which is simply a device (pictured) that works to convert the optical fibre signal into a more conventional electrical one (i.e. an optical modem) that your broadband router can understand (i.e. your router connects to the ONT via a regular old copper Ethernet LAN cable).

Meanwhile, the ONT itself connects back, via optical fibre and some other bits (splitters etc.), to an Optical Line Terminal (OLT) deeper in the network (often at an exchange / headend), which itself then connects into the operator’s core network and helps to manage the end-user connections as part of the wider Passive Optical Network (PON).

However, operator’s often like to ensure that their OLT and ONT kit comes from the same vendor, which enables them to share all the necessary features, have no compatibility problems and also makes it generally easier on the support side. But times are changing and, in particular, the move toward software defined fibre access networks makes de-coupling aspects of the ONT and OLT link more viable, which can reduce the operator’s costs and make future upgrades easier and quicker to deploy.

The latest example of this hails from the Broadband Forum’s new TR-451 (vOMCI Specification) and MR-451 (ONU Management using Virtualized OMCI) standards. The latest specification enables operators to “de-couple the ONU and OLT from control and management purposes, with the Virtualized ONU Management (vOMCI) being introduced as a solution to centralize operations without relying on each OLT to act as a management entity.”

As a result, the operators’ OLT vendors no longer need to be intimately involved in the roll-out of the management services and features provided by the ONU. TR-451 also increases the number of potential ONU vendors, allowing operators to better negotiate the best prices for ONUs. The specification enables easier interoperability testing and on-boarding of ONUs within an operator’s ecosystem and cloud-based network.

Bruno Cornaglia, Co-Director of the SDN/NFV Work Area at Broadband Forum, said:

“The latest specification can be used in the evolution of the management of ONUs, not as a replacement for the management processes and data models already in use by operators but to future-proof their infrastructure while maintaining their investment in existing ONU devices.

Ultimately, ONU management will be more adaptive to changes in operators’ processes and services, as well as less costly to maintain.”

Just to be clear, this moves the OMCI functionality used to manage an ONU – traditionally embedded within the OLT network elements – and shift it into the Operator’s network. Operators that adopt the new approach for future deployments may thus enjoy greater flexibility in how they create, activate, and maintain services associated with ONUs.