vnet/etc/scripts/ip6

packet-generator new {
  name x
  limit 1
  node ethernet-input
  size 64-64
  no-recycle
  data {
    IP6: 1.2.3 -> 4.5.6
    ICMP: ::1 -> ::2
    ICMP echo_request
    incrementing 100
  }
}

tr add pg-input 100