Tuning the Linux kernel for better network throughput

The Linux kernel and the distributions that package it typically provide very conservative defaults to certain network settings that affect networking parameters. These settings can be tuned via the /proc filesystem or using the sysctl program. The latter is often better, as it reads the contents of /etc/sysctl.conf, which allows you to keep settings across reboots.

The following is a snippet from /etc/sysctl.conf that may improve network performance:

net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_syncookies = 1
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.tcp_rmem = 4096 87380 16777216
net.ipv4.tcp_wmem = 4096 65536 16777216

The above isn't to replace what may already exist in /etc/sysctl.conf, but rather to supplement it.

More Here.