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AT&T design for open routing covers many uses

The new AT&T design for open carrier-grade routing covers systems ranging from single line card devices to large hardware clusters. The design taps Broadcom's Jericho2 chip.

Antone Gonsalves
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Published: 01 Oct 2019

AT&T has introduced an ambitious open design for a distributed, disaggregated chassis that hardware makers can use to build service provider-class routers ranging from single line card systems to large clusters of routing hardware.

AT&T recently submitted the specs for its white box architecture to the Open Compute Project, an initiative to share with the general IT industry designs for server and data center components. The AT&T design builds a router chassis around Broadcom's StrataDNX Jericho2 system-on-a-chip for Ethernet switches and routers.

AT&T has been a leading advocate of open, disaggregated hardware to reduce CapEx costs. It plans to use the new design for edge and core routers that comprise its global Common Backbone. The CBB is the network that handles the service provider's IP traffic.

Also, AT&T plans to use the Jericho2 chip in its design to power 400 Gbps interfaces for the carrier's next-generation 5G wireless network services.

For several years, AT&T has advocated for an open disaggregated router, which means the hardware is responsible only for data traffic while its control plane runs in separate software. Therefore, AT&T's new design specs are not a surprise.

"What is indeed interesting is that they are taking the approach to all router use cases including high-performance, high-capacity routing using this distributed chassis scale-out approach," Rajesh Ghai, an analyst at IDC, said.

AT&T design committed to hardware neutrality

AT&T's hardware-agnostic design is ambitious because its use in carrier-class routing would require a new approach to procuring, deploying, managing and orchestrating hardware, Ghai said. "I know they have tried [to develop that approach] in the lab over the past year with a startup."

Whether hardware built on AT&T specs can find a home outside of the carrier's data centers remains to be seen.

"AT&T's interest in releasing the specs for everyone is to drive adoption of the open hardware approach by other SPs [service providers] and hence drive a new market for disaggregated routers," Ghai said. "But this requires sophistication on the part of the SP that few have. So, we'll have to see who jumps in next."

At the very least, vendors know the specifications they must meet to sell router software to AT&T, Ghai said.

AT&T's design specifies three key building blocks for router clusters. The smallest is a line card system that supports 40 100 Gbps ports, plus 13 400 Gbps fabric-facing ports. In the middle is a line card system supporting 10 400 Gbps client ports, plus 13 400 Gbps fabric-facing ports.

For the largest systems, there is a fabric device that supports 48 400 Gbps ports. AT&T's specs also cover a fabric system with 24 400 Gbps ports.

AT&T has taken a more aggressive approach to open hardware than rival Verizon. The latter has said it would run its router control plane in the cloud and use it to manage devices from Cisco and Juniper Networks, Ghai said.

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