By delivering broadband DSL over a CORD network, CenturyLink is advancing toward its goal of virtualizing its access network and central offices, an infrastructure transformation slated to end in 2019 with the arrival of complete global virtualization coverage across its IP core network.
The fixed-line operator uses its own virtualized broadband network gateway (vBNG) and Central Office Re-Architected as a Datacenter (CORD) design to accelerate and simplify delivery of business and residential DSL broadband, said Adam Dunstan, vice president of SDN/NFV engineering at CenturyLink. Despite the nomenclature, the cable operator is not using ONOS CORD; rather, CenturyLink used agile development to design its own central office solution, Dunstan said.
Dunstan, who joined CenturyLink in June 2016 specifically to focus on "Agile" and simplicity, spoke this week to Elizabeth Coyne, managing editor of Light Reading, to discuss the operator's CORD implementation, short- and long-term goals, and the expected, plus surprise, benefits of virtualization to broadband providers and customers. Read on for the edited transcript:
UBB2020: Can you describe CenturyLink's CORD philosophy?
Adam Dunstan: This is all part of the big picture. We use CORD as the architectural word versus a particular standards organization's word because it's a central office redesigned as a data center, and I think people have turned this into products and standards organizations and stuff, and you shouldn't read into this that we've used specific things to go off and build it from that chain -- but we fundamentally believe in CORD as a key to our modernization. It gives us new functions ... that you just cannot do with the current mode of operation. Of course, [there are] cost benefits. It's driven by this fundamental decomposition of these expensive, complicated pieces of equipment and this move to microservices.
UBB2020: What benefits does CORD bring to the table at CenturyLink and why?
AD: In addition to giving us cost and feature benefits, it also gives us simplicity and, inherently, that simplicity gives us reliability, and then makes it easier for us to automate and we end up in a unified place. We see CORD as our path for our access infrastructure. For example, in a CORD model the bill of materials we buy for a DSL location or GPON location is largely the same. Whereas today when we do a DSL location, we'll buy one bill of materials for DSL and that has all its own limitations and constraints. We'll buy a different bill of material for a GPON location. In a CORD infrastructure, one thing will change -- the thing that accesses the physical layer -- but the rest of it remains uniform so we get a lot of uniformity in the platform that we build from both a services and automation and procurement-power perspective.
UBB2020: So is this an R-CORD solution similar to ONOS's?
AD: So yes, this is for residential access. But we don't just see this for residential access. I mean I think there's a little [too] much marketing from standards bodies going on here, but [ONOS] R-CORD is about GPON. We've done this with DSL. We see this as a unifying path. We've been at this for quite a lot time. The term "CORD" probably didn't even exist when engineering started on this exercise and we ended up with the same architecture that CORD is [today].
UBB2020: Where does this announcement fit into your overall virtualization plan?
AD: We've said we're on a path to full virtualization by the end of 2019. This is the first one we have done. We did it in a particular central office location where access was straightforward; it was done in the production network. It's been live. It's moving around. Our intention is to continue to roll it out through the rest of the year.
UBB2020: Where will you implement CORD?
AD: As to which locations, if you think about the fundamental changes you're making when you're rolling CORD from buying a name-your-vendor box, the whole architecture's changing and so we're working our way through all the things we have to change associated with that. So, what will our central offices look like in five years' time? They won't look like what they do today. It's not fair to assume -- we have over 3,500 central offices -- that we'll put CORD in every single central office. Some of these places could just end up being wiring centers over time so we're working our way through this whole exercise as we change the fundamental make-up of our central offices.
UBB2020: Do you find virtualization at the edge is more flexible? What benefits are you realizing?
AD: If you look at the current thing at the edge, the vBNG at the edge of the network, it's a very complex and expensive box. These boxes really have three sets of functions in them. But most importantly, what they do is they butt access up against routing and so what CORD does is separate access and routing functionality, and that's exactly what we do here. It allows us to move functions around in a very different kind of way. It allows us to decompose the platform to make it much simpler, turn it into microservices so we have much smaller failure domains, things like that, and then add services to it, like some of the things the CORD guys talk about. Now that said, we did not specifically use any of the ONOS package software. This was all done with our own software.
UBB2020: What impact did this deployment have on CenturyLink's OSS or BSS?
AD: It didn't impact it at all. We didn't have to do anything. If you think about it, you authorize a customer, you switch them on, you speed them up or slow them down or redirect them to a walled garden -- or hand out a fixed IP address, sometimes you want to hand out statics -- and basically there are six functions, and it's uniform across all the footprint.
UBB2020: Can you tell us which vendors you partnered with?
AD: This complex is made up of white box routers, white box switches and white box servers -- the particular BNG componentry is all run on Intel servers.
— Alison Diana, Editor, UBB2020. Follow us on Twitter @UBB2020 or @alisoncdiana.