US telecommunication giants AT&T and Verizon are betting big on open source and OpenStack. Well, betting is not quite right because they _are_ building their networks on top of OpenStack.\n\n\nDuring the OpenStack Summit at Austin, Sorabh Saxena, senior vice president, software development & engineering at \u00a0AT&T delivered a keynote where he talked about how AT&T has been virtualizing its networking infrastructure on top of OpenStack.\n\n\nFor its part, Verizon recently finished a massive network function virtualization (NFV) OpenStack cloud deployment across five of its U.S. data centers.\n\n\nWhen I asked why Verizon is using open source technologies to build its networking stack, Chris Emmons, director, network infrastructure planning at Verizon told me that, \u201cVerizon is building its next-generation network infrastructure to be totally programmable. We will utilize hardware\/software disaggregation with open interfaces to provide flexibility, promote innovation and guard against vendor lock-in. Open source software and white box hardware will be deployed to encourage competition and reduce cost wherever possible.\u201d\n\n\nVerizon started its NFV project in 2015 and created a production design based on a core and pod architecture that provides the hyperscale capabilities and flexibility necessary to meet the company\u2019s complex network requirements.\n\n\nThe company is currently deploying it in domestic aggregation sites, with international locations to be deployed over the next several months. Verizon is also planning to adopt the design in edge network sites by the end of the year.\n\n\nVerizon worked closely with Red Hat, along with hardware vendors like Big Switch Networks and Dell to create the OpenStack pod-based design that went from concept to deployment of more than 50 racks in five production data centers in less than nine months. Verizon has built the project on OpenStack with Red Hat Ceph Storage and a spine-leaf fabric for each pod controlled through a Neutron plugin to Red Hat OpenStack Platform.\n\n\nWhen I asked about the choice of software vendor, Emmons said, \u201cWe chose Red Hat because it is a leader in the OpenStack community and has a history of leading successful open source projects. We are using Red Hat OpenStack Platform (OSP), Red Hat Enterprise Linux (RHEL) and CEPH as part of our solution.\u201d\n\n\nSome of the challenges that Verizon pointed out they tackled in this project are:\u00a0\n\n\nResiliency at Scale \u2013 The design followed a hyperscale-inspired \u201ccore and pod\u201d approach with a 12-rack pod design replicated at data centers across the United States.\u00a0\n\n\nNo Bandwidth Bottlenecks \u2013 A modern leaf-spine Clos design, using centralized SDN control designed to take the network from spine to leaf to vSwitch and avoid bandwidth bottlenecks.\n\n\nLogical Network Design Flexibility \u2013 The pod design accommodates NFV workloads with unique logical network requirements that share the same physical leaf\/spine fabric and vSwitches.\u00a0\n\n\nReduced Operational Complexity \u2013 Operational complexity is reduced through a simplified lifecycle management of the network control systems relative to the OpenStack control systems.\n\n\nIntegrated Security and Visibility \u2013 The NFV Pod is designed to be compliant and secure against intrusions and other threats, monitoring fabric was used to monitor intra-pod traffic and inline traffic.\n\n\nEmmons told me that Verizon has a plan in place to virtualize all of its directional network elements over the next three years. He added that virtualization is a prerequisite for 5G network elements.\n\n\nWhen I asked about how Verizon contributes to the open source community, Emmons said, \u201cVerizon is incorporating open source wherever we see benefit while meeting the demands of our network. We are a corporate sponsor of OpenStack and are participating in other open source projects to help direct to support highly-reliable provider networks. And, we work with other companies in the ecosystem on additional open source contributions.