>> 	if you know that PMTUD is failing for particular paths, you should
>> 	be able to set a lower path MTU value by using route(8) (use -mtu
>> 	keyword).
>I understand he wants to make this automatic?

	could you be more specific?

	if you are thinking about the following, i can't, or do not want to.
	we cannot do this since we have no idea where the breakage is.
	- if we detect PMTUD failing for particular host (foo/32), turn off
	  PMTUD for foo/24.

itojun