LONGHORN HITS A MAJOR SNAG: In another suit alleging improper conduct by Microsoft (see also the Burst.com saga here and here), Alacritech, which claims to be the sole provider of network acceleration products for Microsoft Windows-based systems, sued Microsoft in Federal District Court on August 11, 2004, alleging that Microsoft's existing and future operating systems containing the "Chimney" TCP offload architecture uses Alacritech's SLIC Technology architecture.

On Wednesday, a district court judge granted the networking and storage software vendor a preliminary injunction that could prevent the world's largest software maker from making, using, offering for sale, selling, importing or inducing others to use its "Chimney" TCP offload architecture. Microsoft is planning to ship its next version of Windows, code-named Longhorn, in 2006.

TCP Chimney, which offloads the TCP protocol stack to a Network Interface Card for better network performance, is slated for use in both Longhorn and in the Scalable Networking Pack for Windows Server 2003.

The suit is based on two of Alacritech's fundamental patents relating to scalable networking: U.S. Patent No. 6,427,171 and U.S. Patent No. 6,697,868, both entitled "Protocol Processing Stack for use with Intelligent Network Interface Device."

According to Alacritech, the company met with Microsoft and described its own Dynamic TCP Offload architecture, known as SLIC Technology, under a non-disclosure agreement in September 1998. Then, in April 1999, at Microsoft's request, it delivered a detailed document describing how SLIC could be integrated with Windows. It then shipped its first product based on SLIC in April 2000.

Microsoft broke off communications with Alacritech in June 1999, according to Alacritech, then presented Chimney in May 2003.