CentOS / Fedora / Red Hat Enterprise / Other Linux distro has weird bug in kernel itself.
I’ve tested this on Linux 2.6.18-92.1.1.el5 x86_64. The default IPv6 route, as configured in /etc file does not work. You need to add it manually using route command.
# ip route add {IPv-6-IP} dev {device}
OR
# ip route add 2000::/3 dev eth2
Now, you can ping to IPv6 site, enter:
# ping6 ipv6.google.com
Sample output:
PING ipv6.google.com(2001:4860:0:2001::68) 56 data bytes 64 bytes from 2001:4860:0:2001::68: icmp_seq=0 ttl=59 time=37.3 ms 64 bytes from 2001:4860:0:2001::68: icmp_seq=1 ttl=59 time=36.7 ms 64 bytes from 2001:4860:0:2001::68: icmp_seq=2 ttl=59 time=36.9 ms 64 bytes from 2001:4860:0:2001::68: icmp_seq=3 ttl=59 time=36.9 ms