With several late CentOS 6.2 systems being built on the network I have been running into network disconnect and performance issues being caused by IPV6. Since I am currently not using it on my network I decided to disable it. Here is what I found from several different resources on the Internet.

We can modify /etc/sysctl.conf:

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1

Disable in the running system:

echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6
echo 1 > /proc/sys/net/ipv6/conf/default/disable_ipv6

or

sysctl -w net.ipv6.conf.all.disable_ipv6=1
sysctl -w net.ipv6.conf.default.disable_ipv6=1