The recent Microsoft WinHEC was a throwback to last year's developer and small business partner trade shows: new announcements by the bushel. Microsoft was tossing so many new acronyms around that newbies were getting dizzy and passing out. (It could happen.)
Because Vista and Longhorn were the most popular topics of press release dogma at the show, most of the new announcements concerned that platform. But there were a few info-morsels flavored for those of us in the here-and-now of Windows Server 2003, too. My favorite among these is the Windows Server 2003 SNP (Scalable Networking Pack).
SNP is a combination of new OS enhancements and APIs aimed at managing big wads of network packets. Mostly, it does this by intelligently moving truckloads of packets that require lots of server-CPU-think cycles to dedicated processing resources. You can think of it as acting similarly to a gamer's video card: All the really hard 3D video traffic gets moved to a graphics processing unit on the card so the main CPU doesn't choke under the load.
There are a number of bits and pieces in SNP, but the three big items are: TCP Chimney Offload, which can move packets to compatible NICs; Receive-side Scaling, which acts as an in-bound load balancer, intelligently moving traffic loads across multiple CPUs; and NetDMA, which provides support for direct memory access technology such as Intel's I/OAT (I/O Acceleration Technology).
SNP is meant primarily for Windows Server 2003, but it also will run on Windows XP Professional x64 Edition. It supports most any CPU, except the Itanium. Those users will need to wait for the Itanium-capable version of Longhorn. That ping aside, SNP does offer significant performance improvement for relatively little effort.
That's primarily because these technologies aren't managed much. Provided they see a compatible network adapter such as Intel's PRO/1000 PT, they'll simply find one another and work. Certain features such as Receive-side Scaling may require tweaking to establish which CPUs are on the hit list for additional load, but generally that kind of tweaking is done through the NIC's software rather than through any new features in Windows Server.
Specific performance numbers, however, are still a mystery. Microsoft intends for SNP to really help only servers suffering from CPU-intensive network processing. That could include big-time Web servers, video processing servers, and of course honking big file or backup servers. Although it's not mentioned in its literature, one assumes that VoIP servers would fall into this category, too. Microsoft estimates "between 20 and 100 percent" reduction in processing overhead and as much as a 40 percent increase in overall throughput.
Generally, when the marketing literature spews out numbers that vague, I tend to cut them in half when setting my expectations. But seeing as how I'm heading to Hawaii for a 10 Gig enterprise switch shootout review, perhaps we'll get a chance to test SNP under some really heavy load generation.
Meantime, as long as you've got a compatible NIC, SNP is one download that really can't hurt the burdened heavyweights in your server farm. It's free (available here), and really just requires some install and testing time to see real benefits. And, for once, we don't have to wait for Vista.