ConSentry, a Silicon Valley startup that says its Internet network switches are more efficient than those of giant incumbent Cisco, has raised a $21 million round of funding.

Switches are components that route traffic from through the wider Internet network.

However, large corporations that buy switches to route their traffic often demand security feature to control access (sometimes called Network Access Control). As networks have become faster, security has become more of a challenge, Consentry said.

ConSentry’s switches are designed from the ground up to include NAC that can continuously control the access levels of users on a network, even at hard-wired LAN speeds. Contractors using a company’s network, for example, would have their privileges set when first logging on, but the network would continously monitor their behavior — not allowing suspicious behavior during the session.

NAC is a growing market, with more customers demanding high-level security for their networks. ConSentry made news earlier this year, when two schools each replaced several dozen Cisco switches with ConSentry products.

Smaller competitors also focusing on NAC include Rainier.

The $21 million funding is Consentry’s fourth round. It was led by new investor Teachers’ Private Capital. Other funds participated, including previous backers Sequoia Capital, Accel Partners, INVESCO Private Capital and DAG Ventures, and new investors Translink Capital and NCD Investors.

Consentry, based in Milpitas, Calif., has almost 100 employees, and has taken about $72 million in funding to date.

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