[nycbug-talk] TCP tuning between FreeBSD and Vista

Jonathan jonathan at kc8onw.net
Sun Nov 2 14:00:22 EST 2008

OK I'm stuck :(

I've been playing with it for two days and I can't for the life of me
get more than 7% utilization of a gigabit link between my laptop and my
file server.  I've gone through man tuning as well as a great deal of
Google searching and here are the settings I've tried tweaking with
their current values.  My current testing is transmitting from FreeBSD
to Vista so I've not messed with receive specific settings on BSD or the
transmit specific on Vista.

net.inet.tcp.rfc1323: 1
net.inet.tcp.sendspace: 1048576
net.inet.tcp.recvspace: 1048576
net.inet.tcp.delayed_ack: 1
net.inet.tcp.sendbuf_max: 262144

TCP Global Parameters
Receive-Side Scaling State          : enabled
Chimney Offload State               : enabled
Receive Window Auto-Tuning Level    : normal
Add-On Congestion Control Provider  : ctcp
ECN Capability                      : disabled
RFC 1323 Timestamps                 : enabled

I even did a wireshark dump which looks fine other than the fact I can't
get higher than 7% Trimmed wireshark trace start follows

[SYN] Seq=0 Win=65535 Len=0 MSS=1460 WS=9
[SYN, ACK] Seq=0 Ack=1 Win=8192 Len=0 MSS=1460 WS=8
[ACK] Seq=1 Ack=1 Win=1049600 Len=0

The window stays at 1049600 for the remainder of the connection.

Am I missing something obvious or does anyone have any suggestions to
try as I'm getting rather frustrated at this point.

Jonathan Stewart

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