Forefront Threat Management Gateway (TMG) and Windows Server 2008 Networking Scalability Features
Several years ago, Microsoft released the Scalable Networking Pack (SNP) for Windows Server 2003 SP1. The SNP included enhancements to the operating system’s networking stack to improve scalability and increase performance. Later the SNP features were included in Windows Server 2003 SP2. Veteran ISA firewall administrators will recall that the SNP adversely affected the operation of ISA, particularly when Network Load Balancing (NLB) was enabled. Since these features were enabled by default, disabling them after installing the SNP or Windows Server 2003 SP2 on an ISA firewall was a requirement. This was accomplished by modifying registry keys or installing a hotfix that disabled the SNP features.
Today, the networking stack in Windows Server 2008 and Windows Server 2008 R2 both include the capabilities originally introduced with the SNP. Instead of modifying registry keys to enable/disable those features as we did in Windows Server 2003, they are now managed using netsh.exe. To view these parameters, enter the following command:
netsh interface tcp show global
As you can see, SNP components such as receive-side scaling, chimney offload, and NetDMA are enabled by default. Thankfully TMG is now fully compatible with all of the scalable networking features. There is no need to disable them unless you have a specific requirement to do so.