Comcast: ONF Trellis software is in production together with L2/L3 white box switches

Jet lagged yet energetic and cheerful, Comcast Senior VP of Next Generation Access Networks Elad Nafshi returned from a motor bike trip in the European alps (via a red eye flight from Frankfurt, Germany to SFO) to deliver an important keynote speech at the  Open Networking Foundation (ONF) Connect 2019 conference in Santa Clara, CA this Friday.  A graduate of Tel Aviv University, Mr. Nafshi has been with Comcast for over 14 years.

Elad announced that Comcast, the leading ISP in the U.S. by subscribers, has deployed the open source ONF Trellis software and reference hardware design “in multiple markets with real customers.” He noted that “This is not a technical trial or PoC. We have not deployed a new appliance. We deployed an entire ecosystem.”

Trellis is an SDN-based, multi-purpose leaf-spine (AKA spine-leaf) switching fabric designed for access-and-edge networks, NFV, and edge cloud applications. It uses the Open Network Operating System (ONOS) open source SDN controller running in an x86 based compute server and the OpenFlow protocol as a “southbound API” (Control plane to/from Data plane) to interface with multiple interconnected white box/bare metal L2/L3 switches.  That configuration is shown in the illustration below.

Image result for illustration of Trellis leaf spine fabric

Comcast, AT&T, Deutsche Telekom, and Infosys collectively authored a reference design for Trellis in April 2019.  Reference designs are “blueprints” developed by ONF’s Operator members (AT&T, China Unicom, Comcast, Deutsche Telekom, Google, NTT Group, and Turk Telekom), to address specific use cases for the emerging edge cloud/broadband and mobile access networks.

“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,”  Nafshi said in a press release. “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,” he added.

While Elad said that Trellis rollouts are accelerating and may “soon come to an area near you,” he declined to answer questions about the locations, size or scale of Comcast’s Trellis deployments.   I talked to Elad after his speech and found him to be very engaging and congenial.


Comcast claims an open source- and a white box-based Ethernet backhaul is integral to its next generation network access strategy.  By using Trellis, Nafshi said Comcast improved network scalability as well as space and power facility efficiencies in its cable head-ends.

Trellis plays a key role in Comcast’s next generation Distributed Access Architecture (DAA) [1] strategy, which uses an Ethernet-based converged interconnect network (CIN).  Comcast is using Trellis within this CIN.

Note 1.  Distributed Access Architecture (DAA) enables the evolution of cable networks by decentralizing and virtualizing headend and network functions. DAA extends the digital portion of the head-end or hub domain out to the fiber optic node and places the digital to RF interface at the optical-coax boundary in the node. Replacing the analog optics from the head-end converts the fiber link to a digital fiber Ethernet link, increasing the available bandwidth improving fiber efficiencies (wavelengths and distance), and directional alignment with NFV/SDN/FTTx systems of the future.


“This has been a multiple year journey from design, to extensive field trails 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,” Elad said.

While Comcast’s conventional network currently relies on embedded routing and switching protocols running on individual vendor specific switches, Trellis software runs in a cloud-native SDN fashion on a cluster of standard compute server nodes each of which implements a centralized control plane via the ONOS SDN controller.  This new SDN based architecture 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.”

“The open source ecosystem created by ONF has collectively established a new ‘Distributed DevOps’ model through the process of trialing, hardening and deploying Trellis with Comcast.  This has established a new formula for open source whereby an operator, ONF and a consortium of commercial entities come together to collectively build and stand behind a deployment,” said Saurav DasVice President of Engineering for the ONF.

Earlier at this week’s ONF Connect 2019 event, Arthur D. Little, AT&T, Deutsche Telekom, and Telefónica released a study that found virtualized, cloud-based architectures can save network operators 40% in capex and 25% in opex.



10 thoughts on “Comcast: ONF Trellis software is in production together with L2/L3 white box switches

  1. Stratum for white box switches:

    ONF has announced that the Stratum™ project has been released as open source. Stratum is now available under the Apache 2.0 open source license, and Stratum is forming the foundation for ONF’s next-generation software defined networking (SDN) work.

    Stratum is an open source, silicon-independent switch operating system for software defined networks that runs on a variety of switching silicon and various whitebox switch platforms. Stratum avoids the vendor lock-in found with today’s data planes that feature proprietary silicon interfaces and closed software APIs that tend to lock operators into using a specific hardware technology. Stratum makes possible easy integration of new devices into operators’ networks, making Stratum the foundation for delivering a minimal production-ready distribution for white box switches.

    Stratum also exposes a set of next-generation SDN interfaces including P4, P4Runtime, OpenConfig, gNMI and gNOI, enabling programmability of forwarding behaviors, zero-touch operations and full automated life-cycle management. This makes Stratum a key enabler for ONF’s next-generation SDN initiative.

  2. As presented Friday in a keynote session at the ONF Connect 2019 conference, a founding analyst of 650 Group presented on the Total Addressable Market (TAM) for open source hardware and software in communications service provider networks.

    The report: Open Source on Communication Service Provider Capital Spending, includes a focus on CORD-based cloud, access and edge data center solutions spanning Broadband Access, Metro Ethernet, RAN, Evolved Packet Core (EPC), Optical Transport, SD-WAN, VPN, SP Router, NFV and CDN.

    “This huge $490B equipment spending opportunity over the next 5 years in communications service provider networks is large but is also complex; and the impact of next-generation SDN is making broadband and 5G deployment easier,” said Chris DePuy, founding analyst for 650 Group. “Operators are now moving to open source on a project and a technology basis gradually. Operators expect to achieve considerable Opex savings while also improving service agility.”

  3. ONF, founded by Deutsche Telekom, Facebook, Google, Microsoft, Verizon, and Yahoo in 2011, originally led the SDN charge with OpenFlow. This allows the control plane to interact with the data forwarding plane (L2/L3 switches or packet forwarding engines which don’t do routing) in an SDN environment.

    But at the time, “we were all trying to figure out what SDN was exactly, and how it was going to solve all these network challenges we have,” AT&T CTO Andre Fuetsch said in his ONF 2019 keynote.

    Fast forward eight years and “SDN is now becoming the network,” he added, touting his own company’s SDN milestone announced today.

    “White box hardware coupled with open source software creates this disaggregated, virtualized, and software-defined environment that finally gives us a chance to survive all this growth and change,” he said. “But it really does more than that — it allows us to get ahead of it.”

    For a dissenting point of view see:

    1. Thanks for your comment. I am NOT an ONF skeptic but am very skeptical of AT&T’s claims (by AT&T Communications CEO John Donovan and CTO Andre Fuetsch) that the mega telco/media company will have virtualized 70% of its network functions and traffic by the end of 2019 and will reach 75% virtualization by end of 2020. During his ONF Connect 2019 keynote, Fuetsch said that “currently 75% of AT&T’s data traffic via MPLS tunnels are under SDN control.”

      After numerous checks with AT&T engineers and techs that work in the company’s COs, I hear that the company has NOT decommissioned any of its network equipment from the likes of Cisco (switch/routers), Juniper (routers), Ciena (optical network equipment), ADTRAN ( and other network access), etc. Last year, AT&T said that Samsung, Ericsson and Nokia would supply its 5G network equipment.

      If AT&T had truly virtualized so much (70 to 75%) of its (access, metro and core) network, then physically realized network functions (i.e. network equipment) would be replaced by virtualization software running on commodity compute servers with many white box/bare metal switches running open network operating systems and under SDN control. The AT&T employees I talked with do not see that happening at all!

      Hence, it appears to be a huge smokescreen/ exaggerated PR campaign for AT&T to be perceived as an “avantgarde network operator” that should get more recognition for being a leader and also command a higher stock market valuation.

      1. AT&T has been working with SEBA in its wired broadband network. It began on the wireline side because it is less complex and has a well-defined customer base, versus an emerging area such as IoT, said Tom Anschutz, distinguished member of technical staff. The skills learned there will transfer to mobile, he said.

        Also, as AT&T and other carriers adopt open-source approaches, they will be able to tap into a bigger pool of potential developers.

        “The folks that are trained for IT or for webscale companies — as we adopt those technologies, those folks are trained for our technologies,” Anschutz said.

        Also see:–core-network-virtualization-next-year/d/d-id/754104

  4. Comcast is keeping its options open in rolling out DAA by using open-source software for a major piece of its architecture in multiple markets. Its decision to deploy the open Trellis fabric, and be public about it, should give other network operators more confidence in open networking, and additional big rollouts like Comcast’s could expand the ecosystem around these technologies so Comcast has more suppliers and developers to tap into in the future.

    Service providers that have been discussing production deployments of open networking systems, such as AT&T and Deutsche Telekom, have been talking about 2020 time frames. Several other operators, including AT&T, Sprint, NTT, China Unicom, Turk Telecom, Telefonica and T-Mobile Poland, are also active supporters of ONF.

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