Beta Draft Confidential
Configuring CBX or GX Logical Ports
QoS Attributes
ATM Services Configuration Guide for CBX 3500, CBX 500, GX 550, and B-STDX 9000 1/19/053-53
Table 3-9. Add Logical Port: QoS Tab Fields
Field Action/Description
Class Displays the name of each service class.
Bandwidth Allocation For each class, choose one of the following from the 
pull-down list:
Dynamic — Select Dynamic to enable the bandwidth 
allocation to change dynamically according to 
bandwidth demands. Dynamic bandwidth allocation 
pools the remaining bandwidth for this logical port. This 
includes bandwidth that has not already been allocated 
to a specific queue or assigned to a connection.
Fixed — Select Fixed to specify the percentage of 
bandwidth you want to reserve for that service class. If 
all four service classes are set to Fixed, ensure that all 
four values add up to 100% so that you do not waste 
bandwidth. 
• If you set the CBR or VBR service class bandwidth 
to Fixed, you are specifying the maximum bandwidth 
to reserve for this type of traffic; if the network 
requests a circuit that exceeds the fixed value, the 
circuit cannot be created.
• If you set the ABR/UBR service class to Fixed, you 
are guaranteeing that amount of service (at a 
minimum) for the UBR queue, provided that the 
VBR queues are not oversubscribed. 100 cells/sec. of 
bandwidth is allocated for ABR/UBR connections.
Note: If you have service classes set to Dynamic, any 
remaining bandwidth percentage is allocated to those 
service classes as needed. For example, if CBR is Fixed 
at 30%, ABR/UBR is Fixed at 25%, and the two VBR 
classes are set to Dynamic, the remaining 45% of 
bandwidth will be dynamically allocated between the 
two VBR service classes.
Fixed At % If you selected Fixed in the Bandwidth Allocation field, 
then for each class enter the percentage of bandwidth 
you want to reserve for that class.
If all four service classes are set to Fixed, ensure that all 
four values add up to 100% so you do not waste 
bandwidth.