Alacritech® Dynamic TCP Offload™

Alacritech was founded to address the impact of TCP protocol processing in data networks by a group of passionate engineers who deeply understood the relationships, from a systems perspective, between the TCP stack, the network accelerator, the host operating system, and the application in driving overall performance. Network traffic processing can have a significant impact on overall system performance. The traditional method by which servers process and transfer data, is both compute intensive and highly inefficient. Alacritech developed a better way to handle TCP traffic using Dynamic TCP Offload technology. This technology has become the standard for today’s Windows® servers and will help drive the next generation of network technology.

The traditional or old method of processing network data started with incoming traffic being received by the network card. The NIC would then interrupt the host CPU which would move the data into the network buffer. The host processor would then move the data from the network buffer and place it into memory appropriate for the application that requested it. With this method, the host processor was repeatedly being interrupted and the data would take multiple trips across the memory bus. This process would take place for each network data packet received by the network card.

Clearly the old method was not an efficient system, yet this had been the accepted method for moving network traffic. Compounding this inherent inefficiency has been the changing landscape of data. Data has increasingly become mobile and is intended for display or viewing, such as HTTP traffic, versus data intended for general CPU processing. Servers aren’t optimized to process such data and applying expensive CPU cycles to such loads greatly limits the system’s scalability. Furthermore, in today’s networks, where multiple gigabit connections are common and IP storage is increasingly being deployed, the impact of network processing on the host CPU has become a significant issue. Clearly, a better solution was needed.

To this end, Alacritech invented Dynamic TCP Offload. Alacritech technology works by offloading the processing of TCP network traffic to a custom ASIC, known as an Internet Protocol Processor (IPP), on the Accelerator. Alacritech Accelerators are “stateful” systems that receive control of the connection and assume responsibility of TCP processing from the host. Data traffic is transferred from the accelerator directly to the application’s memory buffer (be it User or Kernel memory) with great efficiency, requiring no host CPU interaction. Data is delivered with speed and accuracy. The end result is a more scalable server, capable of supporting more clients, hosting more loads, or processing applications faster. A common benefit to customers with this approach is decreased latency. Alacritech customers have seen as much as a 35% decrease in latency when compared to the old method of using a legacy NIC.

In 2005, Microsoft^® and Alacritech announced a cross-licensing agreement. Through this agreement Microsoft^® incorporated Alacritech patented technology into the Windows^® operating system. Microsoft^® refers to this technology as TCP Chimney Offload.