In message <m0vpmgL-0000EfC@flatlin.ka.sub.org>Christoph Badura writes
>Reassembly has always been the responsibility of the receiving host in
>IP.  The whole point of path MTU discovery is to avoid fragmentation
>in the first place.  Besides, a sending host just doesn't send
>fragments in any version of IP, unless it's IP implementation is
>severly broken.  Routers fragment IP packets.

Sure, but you'll still have to fragment UDP datagrams.  One of the
goals of IPv6 was to reduce the load on routers, so fragmentation
is only allowed end-to-end.  No IPv6 router will ever fragment;  if
a packet is too big, it is dropped, and an ICMP Packet Too Big 
message is returned.

Kevin