JEB’s Network Interface Checklist
version 2.4, 2/3/2011

1. Any changes to NIC configuration may cause the network interface to cease connecting for a little while.  If it’s a server, this counts as “server down” for at least a few minutes.  Occasionally, if a driver is old or the machine has not been rebooted in a long time, a reboot may be necessary for the NIC to work again after certain changes are made.  It is generally best to not make changes unless there are performance issues or specific concerns about network behavior — but without these changes, overall performance often goes down more than 50%.
2. Install the most current drivers.  If the NIC is Intel or Broadcom, install the driver downloaded from Intel or Broadcom, not from Dell or other third-party packager.  Often a third-party packager will have separated the application (e.g., “Intel PROset Application”) from the driver (“Intel PROset Driver”); in such a case, the application needs to be removed before the update installation begins.  For Intel drivers, the fastest route for the download is to go to http://downloadcenter.intel.com, search for “prowin32”, and click the link with the latest version (15.1.1 at this writing).  The link will take you to a page with both 32-bit and 64-bit drivers.
3. For Server 2000, Server 2003, and XP, turn all offloading off.  This is actually a requirement, not just a recommendation, discussed in certain Microsoft reference materials.  In one case in the recent past, SBS simply failed to serve file or print to any workstation, unless this was done; in all cases thus far there has been an increase in general network reliability and performance when this is done.  On Intel NICs, this is often under “Performance Options”.
4. For Server 2008, Server 2008R2, Vista, and Windows 7, turn all offloading on.
5. For anything including “Scaling”, set it to “off” or “Disabled”, for 2000, XP, or Server 2003.  This is another Microsoft essential. There is a pack which is included in 2003SP2 which is said to make “Scaling” help, but it does not always help.
6. For flow control, “Respond Only” (or “Rx Enabled”) is preferred, but if this is not available, set it to “On”.  This is not the same as “Rx Enabled” or “TX Enabled” under offloading!
7. For Receive Descriptors and Transmit Descriptors on most NICs, set them to the maximum, unless the server is desperately low on RAM.  For some the maximums are 2048, for some one or the other is 5000, for others it is much less.  Each descriptor takes 2K of RAM.  Some Broadcom gigabit NICs will yellow-flag if they are set to 2048; for these, set receive to 750, transmit to 1500.
8. For Adaptive Inter-frame Spacing, set it to “on” or “Enabled”.
9. In the NIC’s “Power Management” tab, turn everything off.  This may have to be modified if Wake-On-LAN is used.
10. In Server 2008, only one NIC (or one NIC team) is permitted to represent the server on the network. If there are two active NICs, you will have to turn one off, or crashes and unpredictable behavior will result sooner or later.
11. In Server 2008, IPv6 must be turned on, and not deleted. It does not have to be configured, but it must be turned on.
12. It is very much preferable, for Server 2008 and most especially for SBS 2008, for a working IPv6 subnet to be configured, even if the server(s) are the only devices which are able to use IPv6.