SDN company helps build clouds

Contextream offers software for virtualizing content networks

Contextream, a developer of network virtualization software for cloud computing, this week announced the availability of Contextream Grid for cloud and managed hosting providers.

The company's Grid software is designed to enable cloud providers to more easily configure, scale and support multi-tenancy requirements than individually configured hardware appliances and devices. Contextream Grid helps cloud providers optimize physical resources and reduce infrastructure costs in both capital procurement and operational expense, Contextream says.

Grid allows providers to build a software-defined network of distributed virtual Layer 4-7 switches that work as an overlay on existing networks. It virtualizes how operators connect subscribers to content and services, and is designed to overcome the scalability and configuration challenges of VLANs, Spanning Tree and flooding-based address learning.

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It does this by implementing a distributed control plane as opposed to relying on a centralized controller.

A distributed control plane maintains autonomy of network elements to increase reliability and security, eliminate network chokepoints and prevent vendor lock-in, Contextream says.

It also uses a so-called unique "distributed hash" technique rather than flooding to identify new elements as they connect to the network. This allows for scalable networks by eliminating a source of network congestion from address broadcasting, the company says.

With the first packet, each server or virtual machine is classified into one Layer 2 broadcast domain that limits who it can communicate with. Subsequent packets are forwarded within the determined domain.

This overcomes the limitations of a finite number of VLAN domains, Contextream says. In multi-tenant environments, Grid supports tenants' private IP address spaces, allowing for overlapping IP addresses while isolating traffic, the company says.

Grid runs on top-of-rack switches in a data center -- not on a server's virtual switch or hypervisor. And because Contextream Grid is not integrated with the hypervisor, customers can support both virtualized and non-virtualized environments, the company says.

Contextream is a private company founded in 2007. It has raised $29 million and investors include Comcast, Verizon, Norwest Venture Partners, Benhamou Global Ventures and others.

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