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ATM : MBS - VBR NRT How does this actually work?

Hi there,

I am currently testing with ATM VBR-NRT pvcs, and i need to get an understanding of the burst.

My assumption was the following, At Time 0 the pvc has all the tokens, traffic then hits it at rate above PCR, therefore the first X (where X = MBS) cells are sent at PCR, then the remaining are sent at SCR, the only time traffic will go at PCR is when tokens are available to burst.

What I need to know is that is the MBS the total number of cells that can be sent at PCR, and is this in addition to cells that are sent at SCR in the same time? Reason I ask is that there is a tech note on CCO that gives a formula in calculating the burst time which is :=

T = (MBS * 424) / (PCR-SCR)

this equation suggests that the cells sent at PCR are in addition to SCR as it assumes that the time to transmit the cells is a function of the difference between the SCR and the PCR ?

Any help appriciated as I am extremely confused!


Re: ATM : MBS - VBR NRT How does this actually work?

Yes. MBS defines the maximum number of cells above SCR that a source can send at PCR.

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