Re: Port-forwarding Perfomance

[Rudi Starcevic <tech@wildcash.com>]

Hi,


I'm still seeing slow performance with my port-forwarding but
have found something interesting that may be problematic.

Just to re-cap:

I have one Linux 66.283.12.21 box and one Windows box 192.168.0.10
I can download a file of the linux box at around 140K/s
That very same file download on the Windows machine is around 15K/s using DNAT and Masq/Forwarding.

However we can upload to the Windows box at 140k/s.

So it is only slow, 15K/s, when the data is coming from Windows then through the Linux Iptables Masq/Forwarding Firewall.

I contacted an earlier Admin for the Windows machine and was informed the TCP window size has been manually increased.

Could this affect Forwarding in Iptables ?

The default maximum TCP window size in Win2000 is 17520 bytes (12 segments).
The current value is set at 131400.

90% of the traffic being port-forwarded are Digital video files.
These range in size from 2MB to 200MB.

So I assume with large files like these Windows would opt for it's largest TCP window size.

I guess the next step is to lower these to their default values and see if it affect bandwidth.

Your thoughts on that would be much appreciated.

Thanks.
Regards,
Rudi




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