IPv4 MTU detection

Hi there.

I've started working with TTM a few days ago and I'm still sorting out the tecnology and implementation... one thing though that I couldn't find was MTU testing. A large carrier serving our country has suffered this year from a failure mode that was really hard to detect: load-balancing between multiple paths where some of the paths would have a smaller than usual MTU (because it was backup capacity hired from another carrier), and having that measurement would have helped.

I noticed that there is IPv6 MTU testing (http://www.ripe.net/ttm/Plots/pmtu/tunneldiscovery.cgi) available but couldn't find an IPv4 counterpart; is it available somewhere ?

Rubens Kuhl