Case Study: NTT achieves a flexible, simplified, and cost-efficient network with Cumulus Networks' Cumulus Linux

NTT Builds a Flexible and Simple Network with Cumulus Linux

NTT Software Innovation Center (NTT SIC), part of NTT’s R&D and open-source efforts, needed a more flexible, simple network to support rapid innovation and strict SLAs. They were struggling with Layer 2 complexity—network loops, rogue DHCP servers and IP misconfigurations—and required a solution that would integrate with existing tools and custom applications like GoBGP while minimizing operational overhead.

NTT SIC implemented a Clos Layer 3 fabric using Cumulus Linux on leaf and spine switches and Ubuntu on compute nodes, leveraging ONIE/ZTP, Ansible automation (invoked via a custom REST API), EVPN/VXLAN for Layer 2 compatibility, and existing monitoring tools (InfluxDB/Grafana). The new approach enabled running Kubernetes, Calico and GoBGP at the edge, halved CapEx, cut troubleshooting time by 50%, reduced server/host deployment from days to minutes, eliminated custom network tool development, and significantly sped time to production.

NTT

Wataru Ishida

Engineer