Microsoft has announced an add-on for Windows designed to improve networking performance and scalability for such tasks as storage and backup when coupled with specialized hardware.

The Windows Server 2003 Scalable Networking Pack (SNP) is a network acceleration and hardware-based offloading technology that relieves the CPU of certain tasks in order to improve performance. The enhancements, which are being made available as a free download, are specifically targeted at storage, backup, Web hosting, TCP-based media streaming and real-time collaboration.

Users will need to buy a specialised network interface card (NIC) to drive the software enhancements.

Microsoft demonstrated the changes at its annual Windows Hardware Engineering Conference (WinHEC) during a keynote by Bob Muglia, Microsoft’s senior vice president of the server and tools business.

The software and hardware combination is designed to ease networking bottlenecks such as CPU overhead and memory bandwidth related to network packet processing, and reduce the demands put on servers by today’s Gigabit Ethernet speeds.

“Overall we are talking about better performance and scalability for data intensive workloads,” says Ian Hameroff, product manager for Windows Server Core Networking.

Microsoft hopes the improvements mean users won't have to purchase additional servers for their data centers or replace existing hardware in order to boost their networking performance.

The company will offer the SNP software for Windows Server 2003 (Service Pack 1 or later) in both the 32-bit and 64-bit editions and the 64-bit edition of Windows XP Pro.
Hameroff said the operating system changes would not require changes to existing applications, network topology, server configurations, or network management tools.
The SNP architectural changes will be built directly into the next versions of the operating system, the Vista client, due to ship in November to corporate users, and the Longhorn Server, due to ship in the second half of 2007.
Microsoft partners, including Broadcom, IBM, and Dell will supply NICs and preloaded hardware that support the SNP.
Microsoft has made the SNP architectural changes at the network driver interface specification (NDIS) layer. The purpose of the NDIS is to define a standard API for NICs. Microsoft has added three technologies to the NDIS layer - TCP chimney offload, receive-side scaling and NetDMA.
The TCP chimney offload provides stateful offload of TCP traffic processing to network adapters that have a TCP offload engine (TOE). The intent is to reduce CPU overhead by passing tasks such as packet segmentation to the adapter, which can free the CPU to support more user sessions and reduce latency.
The receive-side scaling allows inbound network traffic to be shared across multiple CPUs using the new network interface enhancements. Microsoft says the feature is a benefit to applications that run on multiprocessor machines and generate significant inbound traffic, such as Web hosting or file serving.
The NetDMA feature enables memory management through direct memory access (DMA) offload on servers with technology such as Intel’s I/O acceleration technology.

The three performance and networking changes are just the first that Microsoft plans to make in the operating system.

With Longhorn, Microsoft will improve the administrative control over offload policies and support offloading connections when firewalls and or IPSec policy are used. Microsoft also will include offload support for TCP connections that are IPSec protected. In addition, Vista will include support for IPv6 and NDIS 6.0 APIs that allow multipacket processing on all data ports.

More information on the Windows Server 2003 Scalable Networking Pack can be found here.