Thanks, this doesnt reallt explain the speeds that your guaranteed, and burst speeds, is the CIR the guaranteed speed ? what is the busrt speed defined as ?

Here is a qoute from the above document:

"Committed Information Rates (CIRs) increase network control by providing a mechanism for prioritizing end user data on a per-PVC basis across a given UNI. A CIR allows a sustained throughput at a chosen rate."

By contrast, a burst rate is a maximum unsustainable rate.