Best Network Virtualization Software

Project Calico is an open source project with an active development and user community, and Calico Open Source has grown from it to become the most widely adopted solution for container networking and security. The scale is substantial: the project reports powering more than 8 million nodes daily across 166 countries.

Calico solves networking and security for Kubernetes, where the problem differs fundamentally from traditional networks. Containers are created and destroyed continuously and cannot be addressed by fixed IP rules, so policy must attach to workload identity and labels rather than to addresses.

Performance work centres on eBPF, a Linux kernel technology allowing programs to run in kernel space safely. Using eBPF for the data path avoids overhead inherent to older packet handling approaches, which matters at the packet rates container platforms generate.

The commercial product, Calico Cloud, is a software as a service platform published at 0.025 dollars per vCPU hour and available through Microsoft Azure, AWS and Google marketplaces, which allows purchase against existing cloud commitments. Adoption references include IBM Cloud Kubernetes Services, and the project publishes its GitHub stars, Slack membership and contributor counts openly.

Open vSwitch is a production quality, multilayer virtual switch licensed under the open source Apache 2.0 licence. It is one of the foundational components of software defined networking, providing the switching layer inside hypervisors and hosts where virtual machines and containers connect to the network.

Multilayer means it operates across several layers of the network stack rather than switching frames alone, which is what allows a virtual switch to enforce policy, tunnel traffic and support the overlay networks that virtualised infrastructure depends on. Many higher level SDN platforms use it as their data plane rather than implementing their own, which is why it appears beneath products that never mention it.

Being production quality is the claim that matters most in this position. A virtual switch sits in the path of every packet a host sends or receives, so a defect is not a degraded feature but an outage. Open vSwitch has been deployed at scale in cloud and telecommunications infrastructure for many years.

The project sustains an active technical community, running the OVS and OVN conference series annually since 2016, alongside a further presence at events such as OpenStack Boston. Documentation, manual pages and recorded talks and presentations are published, and the Apache 2.0 licence permits commercial use without a licence fee.

Nutanix Flow brings built in security together with virtual networking inside the Nutanix platform, addressing microsegmentation and zero trust for hybrid clouds. Being built in rather than bolted on is the central claim, since the alternative is inserting separate security appliances into traffic paths.

Nutanix Flow comprises two main features. Flow Virtual Networking provides software defined overlay networks in the form of virtual private clouds spanning on premises and cloud environments. Flow Network Security provides the microsegmentation layer that governs what may communicate with what inside those networks.

Microsegmentation matters because traditional perimeter security assumes threats come from outside. Once an attacker is inside a flat network they move laterally without obstruction. Microsegmentation restricts communication between workloads to what policy explicitly permits, so a compromised workload cannot reach the rest of the estate unchallenged.

Because policy attaches to workloads rather than to network addresses, it follows a virtual machine as it moves between hosts or between on premises and cloud, which is what makes segmentation practical in an environment where workloads relocate constantly. Nutanix serves automotive, financial services, government and education, healthcare, legal, manufacturing, media and entertainment, retail and service providers. Pricing is not published.

Apstra Data Center Director is Juniper's intent based networking system for the data centre, now sold under HPE Juniper Networking following the acquisition of Juniper by HPE. It provides comprehensive management of data centre fabrics from design through to continuous validation.

Intent based networking is the organising idea and it inverts the usual model. Rather than configuring individual switches and hoping the resulting fabric behaves correctly, an operator declares the intended state of the network and the system generates, deploys and continuously verifies the configuration required to achieve it. Drift from that intent is detected rather than discovered during an outage.

Apstra Data Center Director is positioned as the foundation for actionable, real time insights, moving teams from network assurance toward application assurance. That distinction matters because a network can be entirely healthy by its own metrics while the applications running across it are not, and closing that gap is the real operational question.

Juniper supports evaluation directly with a live demonstration, on demand demos, an Apstra Data Center Director datasheet and a Juniper Data Center Assurance datasheet, alongside published material on intent based networking and AIOps for data centre networks. Pricing is not published, which is standard for data centre networking software sold alongside hardware.