AT&T today submitted specifications for a distributed disaggregated chassis (DDC) white box router to the Open Compute Project (OCP).

AT&T is aiming the new DDC design squarely at the provider edge and the core routers that comprise the global IP common backbone (CBB) — the core network that carries all of our IP traffic.

The DDC is based on Broadcom's Jericho2 System on a Chip (SoC), which Michael Satterlee, VP of network infrastructure and services at AT&T, says is ideal for the application "because it has the deep buffers, route scale, and port density that service providers require."

Perhaps more importantly, the Jericho2 chipset has been optimized for 400 Gb/s interfaces. AT&T says this capability will be essential as it upgrades its network.

“We’re entering an era where 100G simply can’t handle all of the new demands on our network. Designing a class of routers that can operate at 400G is critical to supporting the massive bandwidth demands that will come with 5G and fiber-based broadband services," said Chris Rice, senior VP of network infrastructure and cloud at AT&T.

AT&T's DDC white box design calls for three components including two line card systems — one supporting 40 100G client ports and the other supporting 10 400G client ports — and a fabric system with 24 or 48 400G ports. AT&T calls for both line cards to support 13 400G fabric facing ports.

While the carrier's DDC design features the same components used in traditional high-capacity routers, its line and fabric cards are implemented as standalone white boxes each with their own power supplies, fans, and controllers. And, rather than utilizing a backplane to interconnect these devices, the DDC would utilize external cabling.

According to AT&T, this approach will enable improved horizontal scale-out as the system capacity is no longer limited by physical size or the backplane's electrical conductance. This approach also means cooling of critical components is simplified compared to traditional router chassis.

Typical configurations include:

• A single line card system supporting up to 4 Tb/s of capacity.
• A small cluster consisting of a fabric system and up to four line cards with a combined capacity of 16 Tb/s.
• A medium cluster consisting of 7 fabric systems and up to 24 line cards for 96 Tb/s of capacity.
• A large cluster consisting of 13 fabric systems and up to 48 line cards capable of 192 Tb/s of capacity.

AT&T, which joined the open computing group in 2015, is a platinum member of OCP.

This time last year, AT&T submitted specifications to OCP for a cell site white box gateway router designed to transition the carrier from legacy technologies to 5G radio access network technologies.

In fact, during the past year AT&T has gone all-in on open source in support of its planned 5G deployment, announcing plans to install more than 60,000 open source software-powered white boxes in spring 2018.