Ipv6

Vars to set

/etc/sysctl.conf

net.ipv6.conf.all.forwarding=1

/etc/sysconfig/network

...
IPV6_DEFAULTGW=your_ipv6_gw_here
IPV6_DEFAULTDEV=your_interface_here

/etc/sysconfig/network-scripts/ifcfg-eth0

..
IPV6INIT=yes
IPV6FORWARDING=yes
IPV6ADDR=your_host_node_ipv6_ip/netmask

/etc/sysconfig/network-scripts/ifup-ipv6 Replace

ipv6_set_default_route "$IPV6_DEFAULTGW" "$IPV6_DEFAULTDEV" "$DEVICE"

With

ip r a 2000::/3 dev "$IPV6_DEFAULTDEV"
ip r a 2000::/3 via "$IPV6_DEFAULTGW" dev "$IPV6_DEFAULTDEV"
ip r d 2000::/3 dev "$IPV6_DEFAULTDEV"

Talk about it -> [1]