Mike Flasko posted to the Windows Core Networking blog with an entry discussing Winsock Kernel. He points out that it is the successor to TDI, and goes on to say that TDI in Vista is an emulation layer built on top of WSK:
On Windows Vista & Windows Server Longhorn, TDI is still supported for compatibility reasons; however, it has been implemented using a translation layer and thus its performance is sub-optimal resulting in performance degradation for TDI clients. For this reason, as well as others (TDI on path to deprecation, etc — see resource links below), drivers should opt to use WSK whenever possible.
He’s conducting a survey on the blog about WSK adoption. If you have a TDI driver, it would probably benefit you to get involved.
This has that standard everything before Vista is legacy
feel that a lot of us have complained about before; I for one will have to continue supporting TDI for years, and I suspect I’m not alone. We are still shipping code supporting Win98 (although thankfully I’m out of the business of actually writing new Win9x code, but only recently).
Interesting stuff; worth a read.
[...] David Powell from the provided me with some insight about the possibility of downlevel support for WSK, now that TDI is being deprecated. He tells me that the WSK team has been getting lots of requests for Windows XP/2003 support lately, and that it’s high on our list of things to do as soon as we get Vista out the door. [...]