testing bandwidth of big internet pipes

[Arjan Lugtenberg <arjan.lugtenberg () planet nl>]

Hi,

We as a Dutch network provider deliver also ATM lines and other big internet pipes for several big company's over here.
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. 
sometimes it happens we deliver a big ATM line (for instance) and after a couple of hours the customer complains about 
the actual line rate.
These problems has to be tested at the point of delivery so that the customer and ourselves are convinced the right 
line is configured in the ATM backbone. 
The test has to be done in such a way that a full T1 can be pulled to the max.

What kind of bandwidth tests do other people on the list use for these big lines?
Are there any documents written about such kind of tests?

Please let me know.

Regards,

Arjan