Hi Kisito,
I'm not familiar with how these apply to UAC, but in general terms, what you're describing is a form of two rate three colour marking (with some bursts).
Imagine that you define two rates (Rc and Rp). If we're talking leaky bucket mechanisms, then the rate is related to the size of the hole in the bucket (i.e. the rate at which traffic can be transmitted).
While traffic is being transmitted at a rate below Rc, that is considered to be within the Committed Rate.
Between Rc and Rp the traffic is considered to be above the Committed Rate but within the Peak Rate.
Above Rp, the traffic is considered to be in excess.
Going back to the leaky bucket mechanism, bursts are usually used to define the size of the bucket. So, you can fill the bucket up to the maximum burst size (i.e. instantaneously, you receive N packets, which fill the bucket. From that point on, you will empty the bucket at Rate and you can refill it at Rate, but if you exceed Rate at all, the packets are dropped. If you go below Rate for a period, then you have some of your burst back).
Committed burst, Peak burst and excess burst are just the burst sizes that are available while you are in each of those states with your general traffic flow.
With two rates, you can effectively get three colours (or classes) If Actual Rate = Ra, you have
Ra < Rc = within Committed Rate
Rc < Ra < Rp = within Peak Rate
Rp < Ra = within Excess Rate
With one rate, you can only create two colours (or classes)
Ra < Rp = Within Allowed (peak) Rate
Ra > Rp = Within Excess Rate.
Hope that helps.
Guy
