Append the following options to support IPv6. For example,
IPV6INIT=yes
IPV6ADDR=9876:543g:FGHI:5431:ywxz:1a2b:0032:A0Z3
IPV6_DEFAULTGW=1234:f567:ABCD:0001:aBcD:9876:efGH:1111
DEVICE=eth1
ONBOOT=yes
BOOTPROTO=static
HWADDR=01:02:03:04:05:06
IPADDR=192.168.2.1
NETMASK=255.255.255.255
IPV6INIT=yes
IPV6ADDR=9876:543g:FGHI:5431:ywxz:1a2b:0032:A0Z3
IPV6_DEFAULTGW=1234:f567:ABCD:0001:aBcD:9876:efGH:1111