Aryaka, a WAN optimisation startup that relies on cloud-based technology, has finished a $25 million series C venture funding round.

"I know that's kind of old-style, but that's what we want to do, so this money will be primarily used to drive sales and build the brand," said president and CEO Ajit Gupta.

The vast majority of the target market in the WAN optimisation sector hasn't yet been claimed, he adds.

"Ninety-five percent of the target market [for WAN optimization] is untouched," he says. "There's a lot of locations that still need this technology."

The firm claims that it can reduce WAN traffic by 98%, mostly through the use of extensive colocation - Aryaka has 12 major facilities around the world, stretching from San Francisco to Tokyo - and the caching of resources.

"The best transfer is a transfer that never happens," Gupta says, asserting that it's a 100% saving in WAN traffic if a request for a given file can be filled without having to send it through the network. Some applications, he says, can be sped up by a factor of 100 through Aryaka's service.

Gupta says his offering also represents a major cost saving opportunity compared to hardware-based WAN optimisation technology. For about $1,000 per month per office, WAN optimisation can be hosted in the cloud, he says - a better price than the tens of thousands a hardware box costs. He did note, however, that the prices quoted were "approximate," and that particularly high usage could increase Aryaka's monthly fee.

Puri says that the way Aryaka's network handles that caching also adds security.

"We cache at the byte level, so if anybody should get access to the data, they can't really compile it back together," Puri says. Gupta adds that the system uses an IPSEC GRE tunnel configuration, making it difficult to decrypt.

Aryaka came out of stealth mode in 2010, and was one of the first companies to offer WAN optimisation as a service. The latest round of funding saw InterWest Partners and Presidio Ventures join Nexus Venture Partners, Trinity Ventures and Mohr Davidow Ventures among the firm's backers.