Optical Connections Magazine Spring 2023



SDN (Software Defined Networking) is not a new concept, but how to apply it to optical networks? As part of its work in the disaggregation of both fixed and mobile networks, the Open Networking Foundation (ONF) has come up with SEBA, a lightweight platform which supports a multitude of virtualised access technologies at the edge of the carrier network including PON, and VOLTHA (Virtual OLT Hardware Abstraction), a software solution which does exactly as the name suggests. Optical Connections editor Peter Dykes spoke to ONF’s general manager Timon Sloane to find out more about ONF and the development of these projects.

is abstracted out, making it easy to swap out the pizza boxes and get consistent behaviour across a diverse range of devices. Furthermore, today in the PON world, these big chassis are tied to the devices that run in the home. Customers buy a device from provider X, and have to buy a home gateway from the same provider, and the vendors make a lot of margin on the home gateway device, if you get locked in, but we’ve broken that as well. The key protocol is OMCI [ONT Management Control Interface] and we have an open implementation of it that can be offered on home gateways. It’s software that runs in the cloud on the central office side, making it possible to mix and match gateways devices as well as vendors. So it’s about a couple of things. First, it’s about putting the operators in control of the network, rather than selecting a vendor and being beholden to their roadmap. Operators can choose different devices in their supply chain and change them on the fly without disrupting their whole network architecture. It’s also about

How was ONF started and why the VOLTHA project?

complicated, expensive chassis, a lot of slots and vertically integrated, so what VOLTHA and SEBA actually do is take that PON chassis, and instead of making it a big, complicated device that’s configured with rules, they separate the hardware and software. PON has special transceivers and everything needed for a multidrop environment, but take protocol elements like configuring a subscriber, DHCP, or assigning an IP address to a subscriber. In the old world, these were functions that were built into that complicated chassis, and if an operator tried to bring on a second chassis from a different vendor, that simple feature behaved slightly differently in each chassis. That creates multiple complications, especially up at the OSS and BSS layer, where minor changes can have a ripple effect. What VOLTHA does by separating things and running in the cloud and in our open source stack, the hardware layer is simplified into a 1U pizza box device that houses the transceivers and the simple devices. As much functionality as possible


ONF is a pretty unique beast, it’s non-profit and it’s been around for more than 10 years.


It came out of Stanford and Berkeley universities with collaboration from operators like AT&T, Google and Microsoft. Our mission from day one really started with SDN, which was a novel concept when it came out of ONF. We were standardising OpenFlow protocol and the vision was that networking devices had become too large, vertically integrated, expensive, high margin devices. At the time, Cisco routers were million-dollar devices, the size of refrigerators and the view was that cloud operators had started to build things that separated the software and the hardware, meaning they could procure simpler hardware devices and start to run the software in the Cloud. That’s really what SDN was about. It occurred to our community that these techniques could be applied to the PON access network. PON devices are pretty


| ISSUE 32 | Q1 2023


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