>    > 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).
>  This doesn't work for, e.g. web servers with random connects from all
>over. Having received one connection from a client, the odds of a getting a
>second one is high, and there may in fact be 4+ concurrent ones already. 

	we may be able to go through tcb table and mark all the tcp
	connections between the same address pair as "PMTUD broken".  however,
	i don't really like this since PMTUD breakage detection is way too 
	unreliable.  if we have a reliable way to detect PMTUD breakge, "mark
	all connection" approach looks fine for me.

itojun