At the moment we are looking for a good badwidth test within your network
to test the line and to see if the customer gets what he has asked/paid
for.
Have you tried pathload/pathrate?
http://www.cc.gatech.edu/fac/Constantinos.Dovrolis/bw.html
Pathchirp is another possibility
http://www.spin.rice.edu/Software/pathChirp/
Both of these websites have documents that you may find useful, or you can
google on pathrate or pathchirp to find additional documents.
--Michael Dillon