IP6_ADDR_4
SYS(fail, "ip -n %s -6 a add %s/128 dev veth4", ns3, IP6_ADDR_4);
SYS(fail, "ip -6 route add %s/128 dev veth3 %s", IP6_ADDR_4, vrf);
#define IP6_ADDR_DST IP6_ADDR_4