(eth src=00:11:22:33:44:55 type=0x86dd
 (ipv6 nh = 17
  (udp src=1701 dst = 1701
   (l2tp
    (ppp address=0xff protocol=0x0057
     (ipv6 nh=17
      (udp (payload pattern=0 length=8))))))))
(eth src=00:11:22:33:44:55 type=0x86dd
 (ipv6 nh = 17
  (udp src=1701 dst = 1701
   (l2tp
    (ppp address=0xff protocol=0x0057
     (ipv6 ver = 5 nh=17
      (udp (payload pattern=0 length=8))))))))