Tweaking TCP windowsize
Tweaking TCP windowsize
- Subject: Tweaking TCP windowsize
- From: Andreas Fink <email@hidden>
- Date: Thu, 23 Jun 2011 08:38:10 +0200
Hello,
We run a datacenter in Iceland and as such we are transferring lots of data from central europe to/from Iceland.
We realized that we never get over 10Mbps of speed while we have a dedicated point to point 1Gbps link in between.
The problem is that filetransfers over TCP get slowed down by the window size which defaults to 64k. As there is 50ms delay between the sites, the window size does slam the breaks on the speed.
I now want to change the default send window size to 6M so it would give us one full gigabit. However setting it with
sysctl -w net.inet.tcp.sendspace=6442450944
results in
sysctl: net.inet.tcp.sendspace: Result too large
which raises the following questions:
a) what is the maximum value in the standard kernel?
b) how can it be increased
And can the window size not be dynamically expanded once its hit?
I think in todays world 64k is way too low. A lot of destinations are 150ms delays away, simply by the fact they are at the other side of the planet. And speeds above 10Mbps for home users are very common while in the datacenters 1Gbps is common and everyone moves to 10GBps.
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Macnetworkprog mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden