Ha I thought! Has Ken not googled this?! So I did it, and could barely find anything.

I got this from alinux tuning guide at http://www.laukas.com/knbase/linux_special/

6. Networking

Enabling and disabling some of the advanced features of TCP: (Usually it is a good idea for these to be enabled)

/proc/sys/net/ipv4/tcp_timestamps
/proc/sys/net/ipv4/tcp_window_scaling
/proc/sys/net/ipv4/tcp_sack

To enable all these features, for example, do the following as root:

echo 1 > /proc/sys/net/ipv4/tcp_timestamps
echo 1 > /proc/sys/net/ipv4/tcp_window_scaling
echo 1 > /proc/sys/net/ipv4/tcp_sack

Tuning the default and maximum window sizes:

/proc/sys/net/core/rmem_default - default receive window
/proc/sys/net/core/rmem_max - maximum receive window
/proc/sys/net/core/wmem_default - default send window
/proc/sys/net/core/wmem_max - maximum send window

/proc/sys/net/ipv4/tcp_rmem - memory reserved for TCP rcv buffers
/proc/sys/net/ipv4/tcp_wmem - memory reserved for TCP snd buffers

The following values would be reasonable for path with a large BDP:

echo 8388608 > /proc/sys/net/core/wmem_max
echo 8388608 > /proc/sys/net/core/rmem_max
Means nothing to me however...