Table of Contents
Advertisement
•
Idle segment
The OC3port Plus transmits cells at the SCR rate until it reaches the end of its
transmit queue. Then, the OC3port Plus starts again with the stress segment
and the cycle continues.
VBR / BURST Parameter Setup
Many parameters affect the way VBR / BURST works:
•
PCR
Determines the cell transmission rate used in the stress segment. PCR must be
set higher than the SCR setting.
•
SCR
Determines the cell transmission rate used during both the drain and idle
segments.
Low rates for SCR allow the policing algorithm to recover more quickly.
•
MBS
Determines the exact number of cells transmitted at the PCR rate during the
stress segment.
Because the OC3port Plus employs a cell transmission queue that repeats after its
cells are transmitted, care must be taken to allow enough time for the drain
segment to occur.
The OC3port Plus will display a warning when the combination of parameters
cannot be met.
Results
If you have a test device that can plot the cell arrivals of an individual cell stream,
you can see all three segments of the VBR / BURST transmission as illustrated in
the examples that follow.
If you look only at the statistics on the receive filters, the stress, drain, and idle
segments are averaged over time and a simple bandwidth number is present.
This average is close to the average values shown in the examples.
If you can capture cells in the buffer with the time stamps set on, you will see the
exact number of MBS cells arriving at the PCR rate. These cells are followed by
cells at half the SCR rate.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
OC3port Plus ATM Transmission
Note
Appendixes
B
B-5
Advertisement
Table of Contents
