Tcp1323Opts and Network Performance

[cg_from_va]

We are trying to improve DFSR performance over a long fat pipe... East coast
to west coast 45Mbps circuit with 63ms RTT. To be able to fill this pipe
with the 4 threads DFSR gives us, we need to adjust some TCP windows. We
have done so, and need windows larger than 64K to make this work, so we
enabled the Tcp1323Opts = 3 in the registry. We have Confirmed these
settings on both servers, and rebooted (many times) and using Network Monitor
we are checking the TCP headers to make sure things are getting set properly.
We now see the TimeStamps option, but we never see a scale value for the TCP
Receive window. The window seems to always be 64K. This is true for file
copies, FTP, and of course DFSR.

Our servers are Identical:
Dell Server PE2950
Dual Quad Core X5355 @ 2.66Ghz
16GB RAM
Windows Server 2003 R2 (SP2)
Enterprise x64 Edition

I was following this article --> http://support.microsoft.com/kb/224829

and expected to see these options in the packet:
TCP: Window = 65535 (0xFFFF)
TCP: Window Scale Option
TCP: Option Type = Window Scale
TCP: Option Length = 3 (0x3)
TCP: Window Scale = 3 (0x3)
TCP: Option Nop = 1 (0x1)
TCP: Option Nop = 1 (0x1)
+ TCP: Timestamps Option
TCP: Option Nop = 1 (0x1)
TCP: Option Nop = 1 (0x1)
+ TCP: SACK Permitted Option

But I only ever see this:
TCP: Window = 65535 (0xFFFF)
TCP: Option Nop = 1 (0x1)
TCP: Option Nop = 1 (0x1)
+ TCP: Timestamps Option

We are pretty sure larger windows will help. Each process can only push
about 1.5Mbps across this circuit, but adding more process means this scales
in a linear fashion. Unfortunately, there is no option to add more threads
to DFSR.

Any help would be appreciated.

Thanks,
Chris