Sprint’s strategy for virtualization and software-defined networking (SDN) has been less publicly discussed than AT&T’s but has some points in common, including a major inhouse development of a platform which has now been placed in open source, and the use of SDN to shake up its traditional supply chain.
The operator has revealed more details of its NFV (Network Functions Virtualization) approach, which – as for many telcos – is starting with a virtualized evolved packet core (EPC). It has also named two of its suppliers, Metaswitch and Mavenir.
The vEPC work is based on Sprint’s own reference design, called C3PO (Clean CUPS Core for Packet Optimization), which was unveiled in May and open sourced (hosted by the Linux Foundation) in the hope of attracting a developer ecosystem and support from other operators). CUPS (Control and User Plane Separation) is a 3GPP standard. The first use cases are virtualized SMS and MMS messaging traffic, and Sprint’s COO for technology, Günther Ottendorfer, wrote in a blog post: “SMS will be fully virtualized by the end of 2017 and we will deploy the MMS VNF onto the virtual platform during the first half of 2018.”
He added in the blog that the project is replacing standalone platforms with a single NFV infrastructure (NFVi) on which the EPC and IP Multimedia Subsystem (IMS) run as virtualized network functions (VNFs). Virtualizing these on a single NFVI will enable Sprint to scale the core up or down dynamically to support new 5G services, depending on demand.
According to Ottendorfer, Sprint – like AT&T with its Domain 2.0 supplier shake-up – wants to use the new architectures to extend its existing vendor line-up by introducing agile and innovative smaller players.
Its two latest partners will offer VNFs for several elements of the core network/IMS. Metaswitch is supplying the SBC (session border controller), the CSCF (call session control function and the BGCF (breakout gateway control function). Mavenir is providing the TAS (telephony application server), MRF (media resource function) and pDRA (policy Diameter routing agent).
Both of these are interesting choices for different reasons. Like some of the vendors which have joined Domain 2.0 – which has included smaller players, reducing the stranglehold of the biggest OEMs – these two Sprint partners are well established mid-size telco suppliers which have focused heavily on the opportunities offered by the new virtualized networks.
Mavenir has emerged from the very traditional VoIP space and recently acquired the vEPC business of Brocade, which is divesting assets as part of its own acquisition by Broadcom, and which had built this activity around an earlier purchase of Connectem. Mavenir itself is a recently completed mash-up of telco software companies. The original Mavenir company, which focused on wireless VoIP and related products, merged with veteran PBX and VoIP supplier Mitel in 2015. That combined firm was in turn acquired, in late 2016, by Xura, which also snapped up Cloud-RAN start-up Ranzure. The group was rebranded under the Mavenir name early this year and, with a vEPC in its portfolio now, is moving further away from a voice focus and into a broader virtualized network platform. One ambition is to provide the central brains for those virtualized networks, including the software to manage Cloud-RANs and associated vEPCs.
Many independent efforts in these fields are starting with small cells, which can support discrete deployments that allow new techniques to be tested without disrupting the macro network. Mavenir said recently that it was engaged in tests of its RAN software, deployed with small cells, with two operators. Of course, Sprint is one of the operators with the biggest plans to densify its network with small cells.
Metaswitch is also a supplier to Domain 2.0 and a member of the ONAP (Open Network Automation Protocol) open source initiative, based on AT&T’s ECOMP technology. It was a pioneer of the practice of open sourcing technology to speed development of new-style operator platforms, aiming to steal a march on larger rivals with a virtualized IMS. Back in early 2015, it worked with Telekom Austria on a virtualized VoLTE app server project based on Metaswitch’s Clearwater IMS Open Source technology, as well as Connectem (now Mavenir) for the vEPC.
In mid-2013, it open sourced its core IMS code and put it in the cloud, in an initiative called Project Clearwater. A year later, it launched Project Calico, targeted to be part of the OpenStack platform. Metaswitch aimed to move the virtual networking component of NFV from Layer 2 to Layer 3, which would simplify implementation and drive scale.
Implementations of OpenStack at Layer 2 entail the complexity of using Ethernet vLANs or other overlays and tunnels, in order to support legacy enterprise protocols. Layer 3, by contrast, is simpler and more efficient, and that will be important as NFV deployments grow in scale and spread beyond a single data center,argues the vendor. Metaswitch offers Project Calico under a free software licence via Apache, and it takes over the networking function of the default OpenStack system when deployed.
Sprint’s C3PO was unveiled in May. It harnesses 3GPP CUPS (control and user plane separation) but also open source work and Sprint’s own developments. Ottendorfer said at the time: “C3PO revolutionizes the network core and it’s part of our expanded toolbox of solutions to meet the coming wave of data in the years ahead. C3PO is an important part of our NFV and SDN initiative, enabling Sprint to adapt more quickly to market demands and scale new services more efficiently and cost-effectively.”
The result of a four-year collaboration with Intel, C3PO is designed to ease bottlenecks in mobile core packet performance by independently scaling the data plane and control plane. It collapses multiple EPC and SGi LAN elements in a single data plane instance. Intel Labs built the core control plane and data plane virtualized EPC applications, and Sprint developed the SDN controller enhancements.
The EPC application code from Intel is available via the CORD project in ON.Lab, and the SDN plug-ins from Sprint are available via OpenDaylight. Next steps will include work to extend the code to new use cases, including some in the Internet of Things.
Sprint’s decision to release its code on an open source platform is part of the carrier’s commitment to advancing the industry, said VP of technology Ron Marquardt.
“Open source is a model that works,” he wrote in a blog post in May. “Open source development allows for very rapid innovation, with a vibrant community providing a high volume of contributions at a relentless pace. The open source model streamlines processes and removes confusion on specifications and their interpretation because the actual implementation is what matters, not the verbiage of a written document … The lines between open source prototypes and normative standards are blurring, and Sprint will continue to contribute to these advancements in our industry.”