easy way to scan for issues with path mtu discovery?

["Darden, Patrick S." <darden () armc org>]

Hi all,

Does anyone know of an easy way to scan for issues with path mtu discovery along a hop path?  E.g. if you think someone 
is ICMP black-holing along a route, or even on the endpoint host, could you use some obscure nmap flag to find out for 
sure, and also to identify the offending hop/router/host?  What tool would you use to test for this, and how would you 
do such a test?  Is there any probing tool that does checks like this automatically?

Seems to me this happens often enough that someone has probably already figured it out, so I am trying not to reinvent 
the wheel.  All I can think of would be to handcraft packets of steadily increasing sizes and look for replies from 
each hop on the route (which would be laborious at best).  Google has not been kind to my researches so far.

I appreciate any help!
--Patrick Darden