The purchase will allow Microsoft to tap into a growing demand for SSL VPN products, particularly among small and medium-sized firms, said Rob Whiteley, an analyst with Forrester Research in Cambridge, Mass.

SSL's VPNs do not require client side software like IPSec-based VPN technologies, helping them gain popularity in recent years. According to Whiteley, the current market for such products is about US$300 million a year and growing rapidly. The major players in the space include F5 Networks, Aventail Corp. and Juniper Networks Inc., via its acquisition of Neoteris.

Microsoft's acquisition of Whale gives it a company that is considerably smaller in size to those vendors. But the fact that Whale has based its platform on Windows technology -- unlike the others whose platforms are based on Linux -- makes it a good fit for Microsoft, he said.

"I think this puts some pretty good wood behind Microsoft's arrow in terms of getting into the security space," he said.

"It was a right choice for Microsoft," said Zeus Kerravala, an analyst with the Yankee Group in Boston. "Whale has been a pretty small niche player and never really had the impact that Aventail and Neoteris have had.'