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OC3port Plus
Users Manual
Example 2: Three CBR sources using 99 % of the available OC3 bandwidth
configured as follows:
•
7XVIEQ 4'6
•
7XVIEQ 4'6
•
Stream 3: PCR 4 % (5.99), CDV LIM: 20 Cls, Shaper: ON
152.0
141.9
131.7
121.6
111.5
Rate
101.3
in
91.2
Mbps
81.1
70.9
60.8
50.7
40.5
30.4
20.3
10.1
0.0
0.0
VBR / Burst (Variable Bit Rate) Stress Test
A VBR / BURST transmission source is used to check ATM policing algorithms at
their limits. The OC3port Plus, when configured, for VBR / BURST, generates a
cell stream that has three distinct segments:
•
Stress segment
A burst of cells, which are equal in length to the count specified by the MBS
parameter, are transmitted at the PCR rate. This fills the "leaky bucket" (as
defined in the ATM Forum implementation agreements) to the maximum level
acceptable by the ATM policing algorithm.
•
Drain segment
A burst of cells is generated at 1/2 the SCR rate until the "leaky bucket" is
drained to the SCR rate. The number of cells required to do this depends on
the amount of stress supplied in the stress segment and is directly proportional
to the MBS size and PCR rate.
B-4
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'(: 0-1 'PW 7LETIV 32
'(: 0-1 'PW 7LETIV 32
ATM Transmit Stream for EX2.OUT
0.5
1.0
Time in Millseconds
Stream 1
Average = 119.80
Stream 2
Average = 22.48
Stream 3
Average = 6.01
1.5
2.0
za174f.eps
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