Comcast puts open source networking software into production

SANTA CLARA, California — Comcast sent its Senior VP of Next Generation Access Networks Elad Nafshi to the Open Networking Foundation (ONF) conference today to announce that the service provider has rolled out some open source software as part of its Distributed Access Architecture (DAA) buildout.

Comcast has deployed the open source ONF Trellis software “in multiple markets,” and rollouts are accelerating. Nafshi called it “the long and winding road that got us here to virtualization of the cable network.” He declined to answer questions about the size and scale of the Trellis rollout. But, he said, “It is not a technical trial or PoC. We have not deployed a new appliance. We deployed an entire ecosystem.”

Trellis takes a collection of white box switches, and turns it into a spine-leaf fabric. The Trellis software runs on clusters of x86 servers. The software-defined networking technology supports distributed access and edge networks as well as NFV and edge cloud applications. Trellis uses the ONOS open source SDN controller and the OpenFlow protocol.  

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Comcast claims an open source- and a white box-based Ethernet backhaul is integral to its next generation access strategy. The DAA specification calls for an Ethernet-based Converged Interconnect Network (CIN), and Comcast is using Trellis in this CIN role.

The company says Trellis also improves space and power efficiencies in its cable headends.  

While Comcast’s conventional network relies on embedded routing and switching protocols running on individual switches, Trellis software runs in a cloud-native fashion on a cluster of standard compute nodes. This makes network design, deployment, debug and upgrades much simpler, while minimizing network complexity and cost.

“This is real, true production at scale,” said ONF VP of Marketing Timon Sloane. “The design has been vetted and tested and hardened over multiple years. It’s in multiple markets, with tens of thousands of subscribers.”

Sloane said the CIN is “essentially an Ethernet to connect the remote PHY and virtual CMTS. That’s the role Trellis is playing. Trellis is software, running on x86 clusters of servers. This used to be big chassis for incumbent vendors. This is all part of that disaggregation story. Using white box hardware on general purpose compute."

“In collaboration with the ONF and a team of supply chain vendors, Comcast is deploying the open source Trellis platform as the networking fabric in our next generation access network,” said Nafshi. “This has been a multiple year journey from design, to extensive field trials and finally to production rollout, and we’re impressed with the results and the advantages that using open source and Trellis are delivering for us as we upgrade our access network.”