ggsn ggsn0
 apn inet6
  gtpu-mode tun
  tun-device tun6
  type-support v6
  ipv6 prefix dynamic 2001:780:44:2000:0:0:0:0/56
  ipv6 dns 0 fd02:db8:3::201
  ipv6 dns 1 2001:4860:4860::8844
  ipv6 ifconfig 2001:780:44:2000:0:0:0:0/56
  no shutdown
 default-apn inet6
 no shutdown ggsn