>>> 	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.

	aha, put a mark on routing table for foo/32... not sure.  i guess
	defininng RTF_xx for this is too much.

itojun