[105461] in North American Network Operators' Group
easy way to scan for issues with path mtu discovery?
daemon@ATHENA.MIT.EDU (Darden, Patrick S.)
Tue Jun 24 10:28:16 2008
Date: Tue, 24 Jun 2008 10:28:12 -0400
From: "Darden, Patrick S." <darden@armc.org>
To: <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.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
