Encapsulation - E-data DSL-2120 Series User Manual

Sustained Cell Rate (SCR) is the mean cell rate of a bursty, on-off traffic source that can
be sent at the peak rate, and a parameter for burst-type traffic. SCR may not be greater than
the PCR; the system default is 0 cells/sec.
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.
The following figure illustrates the relationship between PCR, SCR and MBS.
CBR is for connections that support constant rates of data transfer. The only parameter
you need to worry about in CBR is PCR.
UBR is for connections that have variable traffic. The only parameter you need to worry
about in UBR is PCR.
rtVBR is for connections that, while having variable traffic, require precise timing between
traffic source and destination. PCR, SCR and MBS must all be set for rtVBR.
nrtVBR is for connections that have variable traffic, do not require precise timing, but still
require a set bandwidth availability. PCR, SCR and MBS must all be set for nrtVBR.

4.2.2 Encapsulation

Select the encapsulation protocol your ISP uses. The following section will vary
depending on which encapsulation protocol you select.
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Revision: V1.0
Page 23 of 86
Apr. 23, 2008