Case Study: Campaign Monitor achieves improved DNS reliability and simplified data-center networking with Cumulus Networks Routing on the Host

Campaign Monitor Builds Networks with Cumulus Networks Routing on the Host

Campaign Monitor, an email-marketing SaaS, needed to boost data center reliability and simplify networking to meet uptime SLAs. With strong in-house Linux expertise and an anycast DNS design, the operations team wanted a more economical, automatable approach that removed fragile layer‑2 dependencies and reduced operational complexity.

They deployed a Clos layer‑3 fabric with Cumulus Linux and used Routing on the Host with Cumulus Quagga (BGP unnumbered) to advertise anycast /32 DNS addresses from hosts. The change brought better DNS locality and redundancy, faster failover, fewer IPs to manage, and the ability to treat switches like servers—eliminating MLAG/STP/FHRP, lowering cost and complexity, and improving availability of critical services.

Campaign Monitor

Tynan Young

Sr. Network Engineer