Arista Networks bought SDN vendor Big Switch Networks, according to sources familiar with the deal.

The purchase is Arista’s largest acquisition to date, according to a source. It’s also the networking vendor’s third acquisition: Arista in 2018 snapped up cloud-managed WiFi firm Mojo Networks and then a month later bought Metamako, a provider of low-latency field programmable gate array (FPGA) products.

While Arista ultimately won, Big Switch had a long list of suitors that wanted to bring its technology in house. Several incumbent networking players, including Cisco, Dell Technologies, VMware, Juniper Networks, and Extreme Networks held “multiple meetings” with Big Switch over the past few months, according to a source.

Big Switch previously partnered with Dell on its open networking product line, which takes aim at proprietary vendors including Arista and Cisco.

The deal is a big one in part because Big Switch’s hybrid cloud visibility and security product, Big Monitoring Fabric (Big Mon), fills a major gap in Arista’s cloud portfolio. This is important as enterprise customers increasingly adopt multicloud environments and need tools to monitor and orchestrate workloads across their data centers and in public clouds. It also puts Arista in a better position to more directly compete against Cisco and its multicloud play.

Big Mon for Public Cloud is a cloud packet broker that provides security and performance monitoring of on-premises, edge, and cloud-native applications. It supports Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform (GCP). And it works like this: First, a cloud-based controller enables AWS and Azure workload discovery, automatic monitoring, analytics, and centralized policy configuration consistent with on-premises deployments.

Then, it uses a lightweight software agent that installs automatically on cloud instances selected for monitoring, which acts as a security tool. This mirrors the traffic from the workloads to send it to Big Switch’s cloud for further processing.

And finally, it uses virtual switch software managed by a cloud-based controller. This filters traffic received from one or more of the software agents, optionally applies packet-modification functions, and delivers the resulting traffic to the cloud-based centralized tool farm.

In addition to Big Mon, Big Switch last year rolled out new hybrid-cloud products and features as part of its Cloud First Networking portfolio. These products aim to bring the best of public cloud (elasticity, speed, and cost savings) to customers’ data centers and then also extend these same networking and monitoring tools across hybrid-cloud environments. The new products included Global VPCs (G-VPCs) and a cloud-based service of its Multicloud Director orchestration tool.