At WinHEC 2006 conference Microsoft surprised network administrators launching, with immediate availability, the Scalable Network Pack for Windows Server 2003 Service Pack 1.
The update is able to greatly improve operating system network performance when a special network card, so called TCP/IP Offload Engine (TOE), is installed in your server (and its manifacturer developed relevant drivers).
A TOE, but also a recent Intel I/O Acceleration Technology (I/AOT) powered motherboard, has a dedicated CPU for handling TCP/IP operations, unloading them from the main processor.
In particular the SNP offers 3 critical features:
- TCP Chimney Offload
TCP Chimney Offload provides automated, stateful offload of Transmission Control Protocol (TCP) traffic processing to a specialized network adapter implementing a TCP Offload Engine (TOE). The stateful capabilities-meaning that the network adapter retains in memory the significant attributes of a connection, such as IP address, ports being used, and packet sequence numbers-significantly reduce the need for CPU cycles in managing offloaded traffic. For long-lived connections with large-sized packet payloads; like those associated with storage workloads, multimedia streaming, and other content-heavy applications; TCP Chimney Offload greatly reduces CPU overhead by delegating network packet processing tasks, including packet segmentation and reassembly, to the network adapter. This frees up CPU cycles for other application tasks, such as supporting more users sessions or processing application requests with lower latency. - Receive-side Scaling
Receive-side Scaling enables the processing of inbound (received) networking traffic to be shared across multiple CPUs or cores by leveraging new network adapter enhancements. Receive-side Scaling can dynamically share the inbound network traffic as either system load, or network conditions vary. Many scenarios--including Web servers, file transfers, block storage, and backups--require the host protocol stack to perform significant work in the context of receive interrupt processing and deferred procedure calls (DPC). In these scenarios and others, Receive-side Scaling can significantly improve the number of transactions per second, the number of connections per second, or total network throughput. - NetDMA
NetDMA enables support for advanced direct memory access technologies, such as Intel I/O Acceleration Technology (I/OAT). For servers equipped with the supported technology, NetDMA provides memory management efficiencies and network packet processing enhancements.
At the heart of NetDMA is the ability to more efficiently support network data movement and reduce system overhead by minimizing CPU involvement in performing memory-to-memory data transfers. Normally the CPU is extensively involved in moving network data from network adapter receive buffers into application buffers. NetDMA largely frees the CPU from handling memory transfers by supporting use of a DMA engine. The DMA engine frees the CPU from the mundane task of copying data so that it can be better used by other applications.
Every Microsoft security professional out there probably had just one thought: Windows Server 2003 SP1 + SNP + ISA Server 2004.
It's not the case: the three mentioned features are automatically disabled when ISA Server is installed on your system.
It is bad? Can be worst: you lost all mentioned features even if you just enable the Windows Server 2003 SP1 Windows Firewall.
Have we to rely on the next ISA Server? Again, it's not the case: neither the upcoming ISA Server 2006 will gain any advantage from the SNP.
