Adjusting the CAC
About the Customizable CAC Options
ATM Services Configuration Guide for CBX 3500, CBX 500, GX 550, and B-STDX 9000
1/19/05
A-3
Beta Draft Confidential
About the Customizable CAC Options
The customizable CAC implementations enable you to directly control the amount of
bandwidth reserved for VBR-NRT and ABR circuits. In addition, you can control the
amount of bandwidth reserved for VBR-RT circuits if you choose the “customize
VBR-RT, VBR-NRT, and ABR” CAC implementation. You control the amount of
bandwidth reserved based on either the physical port type, the SCR requirements of
the circuit, or both. When you use the customized CAC options, the following formula
determines the amount of bandwidth required for a given circuit:
Bwidthreq = SCR*F1*F2
where F1 is the physical port factor (entered as a percentage) and F2 is the SCR scale
factor (entered as a percentage). You can configure only an F1 factor, only an F2
factor, or both factors. If you do not configure one of these factors, then the value of
that factor is, by default, 100%.
Customizable CAC Example
A circuit request is made, and the circuit needs to reserve bandwidth based on an SCR
of 10,000 cells per second (CPS). You configure the F1 factor for DS3 ports at 150%,
the F1 factor for OC3c ports at 80%, and the F2 factor for circuits with an SCR from
8,001-15,000 CPS at 80%. In this example:
•
If the circuit request is made on a DS3 port, then the circuit bandwidth
requirements are based on an SCR of 12,000 cells/sec, instead of 10,000 cells/sec
(10,000 x 150% x 80% = 12,000).
•
If the circuit request is made on an OC3c port, then the circuit bandwidth
requirements are based on an SCR of 6,400 cells/sec (10,000 x 80% x 80%=
6,400).
Note – On frame cards with priority frame capability, the Bwidthreq=SCR.
Summary of Contents for CBX 3500
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