IES-1000 User’s Guide
Virtual Channel Management 13-5
Sustained Cell Rate (SCR)
Sustained Cell Rate (SCR) is the mean cell rate of each bursty traffic source. It specifies the maximum average
rate at which cells can be sent over the virtual connection. SCR may not be greater than the PCR.
Maximum Burst Size (MBS)
Maximum Burst Size (MBS) is the maximum number of cells that can be sent at the PCR. After MBS is reached,
cell rates fall below SCR until cell rate averages to the SCR again. At this time, more cells (up to the MBS) can be
sent at the PCR again.
Minimum Cell Rate (MCR)
Minimum Cell Rate (MCR) is the minimum rate at which the sender can send cells
If the PCR, SCR or MBS is set to the default of “0”, the system will assign a maximum value that
correlates to your upstream line rate.
The following figure illustrates the relationship between PCR, SCR, MCR and MBS.
Figure 13-2 PCR, SCR, MCR and MBS in Traffic Shaping
Cell Delay Variation Tolerance (CDVT)
Cell Delay Variation Tolerance (CDVT) is the accepted tolerance of the difference between a cell’s transfer delay
and the expected transfer delay. CDVT controls the time scale over which the PCR is enforced. CDVT is used to
determine if a cell arrived too early in relation to PCR.
