Pluribus has raised a monster Series D funding round of $50 million led by Singapore sovereign wealth fund Temasek and including Ericsson as a strategic investor.

The Palo Alto, Calif-based company, which focuses on a converged software-defined networking (SDN) platform based on x86 server hardware, says the money kicks the company up a notch in the battle against giants such as Cisco and VMware. The impressive roster of investors includes prior venture investors New Enterprise Associates (NEA), Menlo Ventures, Mohr Davidow, and AME Cloud Ventures. Newtech, an Asia data-center infrastructure provider, also joined as a strategic investor.

The investment was an "up round," according to Pluribus officials, meaning it took on money at a higher valuation than the prior round. Pluribus was ranked in the top three of SDN startups in the Rayno Report's 2014 SDN Report, with a valuation estimated then around $200 million. Although the company did not disclose the valuation, it's likely this round catapulted Pluribus significantly higher, potential above $500 million, according to sources in the industry.

Pluribus CEO Kumar Srikantan says this investment round and roster of partners will take the company to the next level.

"Temasek was an investor in Alibaba," said Srikantan, in an interview on Tuesday. "When they come in they will fuel the fire. They have deep pockets they will come in again and again."

Temasek is a global giant, with a $180 billion portfolio. It's the "Berkshire Hathaway of Singapore," according to Srikantan.

Srikantan said that Newtech, a key distributor of open networking gear in China, is another key partner. Newtech is pursuing the open, SDN model for building out "white box" switching platforms. Ericsson rounds out a strategic roster of partners in the technology world that already includes Tibco Software, Super Micro, and Oracle.

The Pluribus CEO said it was necessary to go big as a startup playing in the market with VMware and Cisco. He believes that the momentum is gaining for SDN startups as some customers question Cisco's hardware-based business model. He pointed out that Pluribus is focused on licensing the software to distributors, who can opt to build their own boxes based on Pluribus' Netvisor software or OEM Pluribus' own hardware products.

"We're tying to build a technology architecture that brings open source and programmability and taking the high scale of computing to the networking market," said Srikantan.

Stressing the software model appears to be key to Pluribus' evolving story. The company sees its Netvisor OS as a bridge between bare-metal switching and SDN and network functions virtualization (NFV) applications, including analytics, switching, fabric management, virtual firewalls and other functions.

The deal should buoy spirits in the SDN startup market, where many sources see 2015 as a shake out year for the upstarts. It also builds on the success of other startups that have raised money for products in the white-box SDN switching market. For example, Pica8 raised $12.5M in Series B funding in October.