>This makes me think our IPv6 stack might have a problem detecting when
>it needs to send smaller packets (path MTU detection).

	as far as i know, there's no bug in PMTUD code (it works fine in my
	environment).  i can think of the following reasons:
	- if there's any router which filters ICMPv6 packet between you and
	  ftp.netbsd.org, you can experience the problem as described above.
	- if there's pair of routers that have tunnel between them, and with
	  MTU configuration is different, you may experience the problem.
	  i have confirmed that you have some problem if you establish tunnel
	  between juniper (MTU = infinty) and KAME (1280).  if you set juniper's
	  MTU to 1280, it works just fine.

itojun