Has anyone run into an issue with the new MS "enhanced" TCP/IP stack?

Essentially what happened was that over the weekend I upgraded all of my Win2k3 DC's to SP2. Come Monday, myself and two other co-workers (the only ones currently running Vista) noticed that any and all network traffic from our hosts to the DC's was painfully slow!

Remote Desktop was the first thing noticed. Followed by file transfers and even network logins. XP systems did not see this or any issues and all the logs were clean. Even dcdiag /v /e reported nothing out of the ordinary.

What sent me over the edge was the fact that my 'LOGONSERVER' variable was set to a DC located in a different AD site! My system knew the site/subnet it belonged to and was supposed to look for DC's in. Instead it decided to look past the 3 local (and online) ones for the remote DC!

After some digging I found out about Vista's TCP/IP Receive window auto-tuning, which supposedly can dynamically adjust the send/receive windows to up to 16mb based on network conditions.

In any case shutting this down immediately fixed the issue for me:

netsh interface tcp set global autotuninglevel=disabled

Was this "enhanced" stack part of SP2 for Server 2003? I haven't been able to verify this. If not, why did the problem only manifest itself on the Vista systems after the DC upgrades?

Keep in mind that at Microsoft itself, Vista clients coupled with 2k3 SP2 servers is an extremely common configuration, perhaps the majority situation by now. If what you described were true for every vista client coupled with 2k3 servers, most of the campus would be having the problem. So I'm guessing the issue is something slightly more complicated than that.

I'm glad you found a good work-around with that netsh command. Was that in a KB article somewhere that you found it?

I don't believe 2k3 SP2 did any major overhaul of the network stack. I'm pretty sure it was only minor bugfixes.

Frequently these kinds of things can be traced down to problems with the firmware on routers and switches, and the problem is usually very subtle and hard to track down. If it only happened after the SP2 upgrade, it's probably just a tiny little thing that set off some subtle bug somewhere.

At least on my network, I have to turn autotuning off to get firefox to run at a decent speed on any Vista machine. Other non-microsoft software such as AVG also runs unbearably slow with it on. As soon as I turn it off, everything is back to normal.

...Was that in a KB article somewhere that you found it?

No nothing anywhere in technet or in a KB article. Actually I happened onto it (google) because other users were seeing the problem in regards to SP2 and slow Remote Desktop sessions.

I was actually at a local MS office today for a propaganda session on SCCM 2007. While I was there I asked my technical resource about it. He had never heard of the Remote Window Auto-Tuning.

Actually a friend of mine working at a local courthouse saw the same issue... He went back to XP!

While I agree that we're more likely the exception rather than the rule...

Nice job M$!!!

Edit: Found this KB article (somewhat) about the issue.

...I have to turn autotuning off to get firefox to run at a decent speed on any Vista machine.

Good to know I'm not the only one missing out on the 'benefits' of the new stack.

I'm starting to wonder if the actual NICs are supposed to be able to support it but don't.

...When switches use 802.1x authentication to control routing...

I actually disabled 802.1X on the DC's to test. Didn't help my issue anyway (not that disabling was a good thing in the first place.)