The new year is off to a good start for SDN startups, as Plexxi and Cumulus become the third and fourth companies to announce funding.

GV, formerly known as Google (Nasdaq: GOOG) Ventures, invested an undisclosed amount in Plexxi , the SDN startup said Wednesday.

Google expects Plexxi to develop tools for large-scale networks providing agility and efficiency, says GV General Partner Rich Miner in a statement from Plexxi. In other words, Plexxi helps build New IP networks.

Plexxi raised $35 million in a D funding round in September, bringing its total funding to $83 million. (See SDN Startup Plexxi Raises $35M for 'Invisible' Networks.)

Plexxi sells software and programmable software-defined hardware switches used in data centers based on OpenStack and VMware Inc. (NYSE: VMW) for campus-wide connectivity, federating multiple data centers in a single image, and widely distributed clouds.

Meanwhile, Cumulus Networks , which makes a Linux operating system for white box switches, scored a $35 million in a C funding round from existing investors Andreessen Horowitz, Battery Ventures , Sequoia Capital , SV Angel, and new investor TopTier Capital, a company spokesman said in an email.

But the news for Cumulus isn't all good. "The valuation of Cumulus has fallen below what it was two years ago for an earlier round," according to a report on VentureBeat, attributing the information to CEO and co-founder JR Rivers.

The company declined to confirm the lowered valuation, but said "revenue and growth in the customer base are tracking well." Cumulus has about 375 customers of all sizes in the US, EMEA, and Asia Pacific, "including a Fortune 50 telco and many of the largest web companies in the world," the spokesman said

The spokesman referred Light Reading to Crunchbase, which reports total equity for Cumulus, founded 2010, at $86 million from 11 investors, with the most recent round January 13.

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Dell Technologies (Nasdaq: DELL) is a prominent partner for Cumulus. Dell this week announced its own Linux operating system to run on its own switches, but said it continues to expect a strong partnership with Cumulus as well. (See Dell Sets Stage for Software-Defined Data Center and Dell Opens Arms to Cumulus OS)

This week, Big Switch Networks announced a $48.5 million Series C funding round, and last week SD-WAN startup VeloCloud Networks Inc. announced a $27 million C round from backers, including Cisco Systems. (See SDN Startup Big Switch Lands $48.5M Funding and Cisco Joins $27M Round for SD-WAN Startup VeloCloud.)

— Mitch Wagner, , West Coast Bureau Chief, Light Reading. Got a tip about SDN or NFV? Send it to [email protected].