int ipip_del_tunnel (u32 sw_if_index);
int sixrd_add_tunnel (ip6_address_t * ip6_prefix, u8 ip6_prefix_len,
ip4_address_t * ip4_prefix, u8 ip4_prefix_len,
int ipip_del_tunnel (u32 sw_if_index);
int sixrd_add_tunnel (ip6_address_t * ip6_prefix, u8 ip6_prefix_len,
ip4_address_t * ip4_prefix, u8 ip4_prefix_len,