AT&T to deploy a white box router per cell site, bringing openness to the edge

AT&T has been the most dogged exponent of open source and commodity technology in the carrier network, from management and orchestration software to the boxes themselves. In recent months, it has revealed results of its multiyear tests of white box routers and switches, which could transform the capex and opex costs of its networks and allow it to build truly multivendor systems.

Now the telco says it will go ahead with a deployment of 60,000 white box routers, to be installed in its cell towers “over the next several years”. That would equate to about one router per cell site (AT&T has 60,000 towers and 5,000 central offices).

Andre Fuetsch, its CTO, and president of AT&T Labs, said in a statement: “White box represents a radical realignment of the traditional service provider model. We’re no longer constrained by the capabilities of proprietary silicon and feature roadmaps of traditional vendors.”

That was an unequivocal throwing down of the gauntlet to those traditional suppliers, challenging them to match the cost bases of open platforms or be sidelined in the operators’ next generation deployments. They will need to offer superior price/performance ratios than those promised by the new telco approach, which combines commoditized open platforms with investment in inhouse software to add value. The latter adds cost too, but enables the carrier to keep control of the aspects of the network which will differentiate its services.

As Patrick Lopez, VP of networks innovation for Telefónica, said, the difference this time around is that “all the operators involved have skin in the game. They are investing not only time and money and network but they actually have teams of people that are developing code, and writing open sourcecode … This is a strong signal to the market showing that beyond intent there is actual effort, progress and code being developed to show the way we would like networks to evolve.”

Fuetsch added: “We’re writing open hardware specifications for these machines, and developing the open source software that powers these boxes. This means faster hardware upgrades, since anyone can build to these specs. And software upgrades that move at internet speed. We’re doing this all while keeping costs low so we can focus on expanding our nationwide mobile 5G footprint for our customers as quickly as possible.”

By pushing white boxes and open software out beyond the core and transport networks and into the cell sites, AT&T is extending virtualization throughout its wireless RAN in preparation for a fully software-driven 5G network with a heavy focus on edge computing, integrated with connectivity (see separate item). White box routers can reduce the cost of delivering wireless connectivity but also provide an affordable way to distribute 5G and cloud services to the edge.

These routers will run the dNOS (disaggregated network operating system) which AT&T invented, based on its acquisition of Vyatta, and plans to open source via the Linux Foundation, like other developments such as ORAN and ONAP.

AT&T has not yet announced its white box router suppliers. It has also tested white box switches and CPE, the former powered by dNOS and the P4 open programming language, which has replaced Openflow as the Open Networking Foundation’s default protocol for switching. Chip vendors including Broadcom, Barefoot, Cavium and Mellanox now make merchant switch-chips for white box platforms, and AT&T has tested systems with the first two of those suppliers. Quanta and Delta are among the first companies to make white box switches themselves.

A year ago, Fuetsch demonstrated the use of P4 on merchant silicon for a white box switch, saying in a conference keynote: “This is more than just about lowering cost and achieving higher performance. Frankly that’s table stakes. This is really about removing barriers, removing layers, removing all that internal proprietary API stack that we’ve lived with these legacy IT systems, now we can bypass all of that and go straight to ONAP” to achieve fine-grained per-packet visibility.

AT&T has worked with Barefoot Networks and SnapRoute on its switch. Barefoot provided its Tofino chip and surrounding software, while SnapRoute (in which AT&T is an investor) developed the network operating system, Flex Switch.

Fuetsch said the firm “took this very novel approach of building a hardware abstraction layer and running open source networking modules like BGP and OSPF on top”. This layer can then operate independently of the silicon, and AT&T said it has other white boxes, based on different chips, in the works, with the same network OS.

With the white paper to launch dNOS as an open platform, AT&T laid down the same gauntlet to vendors, promising “a new approach … for router platform development and procurement”, and saying AT&T will “evolve its router platform sourcing process to give preference to dNOS vendors whose products (or committed product roadmap) are based on using this platform.” This is a big deal for vendors – AT&T claims to have “100,000 interconnected IP/MPLS routers” in its networks.

dNOS is likely to become part of a broader open source effort, like AT&T’s ECOMP (now the basis of ONAP) and XRAN (now in ORAN) before it. At its Open Networking Summit last week, the Linux Foundation’s networking arm, LFN, launched DANOS, an open network OS for white boxes and switches which, the Foundation hopes, will bring together several existing projects, including Free Range Routing and dNOS. This would result in an “uber-operating system” for white boxes that should accelerate commercialization, said Arpit Joshipura, general manager of networking for the Linux Foundation.

In a blog post, Chris Rice, SVP of AT&T Labs’ Domain 2.0 architecture and Design activity, enlarged on the need for a white box OS, writing  on a blog post: “While ONAP is the orchestration software for the entire network, each individual machine also needs its own operating system. We want to get hardware and software makers, open source developers, telecom companies, standards bodies and others to others to start thinking about how we can all push this concept forward.”

AT&T says in its white papers that it has three main objectives for dNOS:

  • Faster introduction of technologies, designs and new features enabled by a collaborative and open ecosystem.
  • Flexibility in network design and service deployment with plug-and-play hardware and software components that can scale up and down cheaply and responsively.
  • Cost reduction by using merchant silicon and standardized hardware and software technology, which will enable very large numbers of elements to be deployed to support high capacity, device density and ubiquitous coverage.

AT&T says that, to achieve all this, “it’s critical that both hardware and software include standardized interfaces that a community of developers can coalesce around. A single, standardized NOS is the most efficient and effective means to this end. A single NOS allows for qualification of a common, shared integration infrastructure and APIs to help developers rapidly launch new applications. It allows for ecosystem developers to focus on value adding applications rather than the basic building block components required in all network infrastructure.”

All this will, operators hope, add up to a transformed cost base and supply chain for 5G. As Fuetsch said: “Here’s the big message for the OEMs. It is really a call for them to open up their architectures, open up their software and their own hardware so they can participate. They are going to have to make a choice here – do you want to be at the table or on the plate?”