Beta Draft Confidential
3-561/19/05 ATM Services Configuration Guide for CBX 3500, CBX 500, GX 550, and B-STDX 9000
Configuring CBX or GX Logical Ports
QoS Attributes
Setting SVC QoS Parameters
The SVC QoS feature enables you to limit the percentage of logical port bandwidth
that SVCs are allowed to consume. This feature is useful in cases when you want to
offer both SVC and PVC services on a logical port, yet limit the amount of bandwidth
available for SVCs. When you configure a logical port for use with SVCs, you have
the ability to set the percentage of bandwidth available for SVCs for each class of
service (CBR, VBR-RT, VBR-NRT, ABR/UBR).
The values entered in the General tab fields in the Configure SVC dialog box
(Figure 17-3 on page 17-4) work in conjunction with the service class bandwidth
allocation values entered in the QoS tab fields in the Add Logical Port dialog box
(Figure 3-20 on page 3-52). From the Configure SVC dialog box, the General tab’s
Bandwidth Allocation field is set to Dynamic by default. If you change the Bandwidth
Allocation field to Fixed and enter a value of (for example) 40% for VBR-NRT, the
logical port bandwidth available for SVCs would be a maximum of 40%. You can
limit the VBR-NRT bandwidth further by entering a value in the QoS tab’s SVC
Allowed (%) field on the Add Logical Port dialog box.
If you accept the default SVC allowed percentage of 100% for all QoS classes, then
SVCs will have the same access as PVCs to the logical port bandwidth in each QoS
class. If you want to limit the amount of logical port bandwidth that SVCs consume,
you must enter a value lower than 100% in the QoS tab’s SVC Allowed (%) field. For
example, if you want to limit CBR SVCs to consume 50% of the logical port
bandwidth available to CBR connections, enter 50% in the QoS tab’s SVC Allowed
(%) field.
The values entered in the QoS tab fields in the Add Logical Port dialog box will also
work in conjunction with port oversubscription. For example, if you oversubscribe a
logical port class of service to 200%, the associated increase in bandwidth is fully
available for SVCs (by default). If you want to limit access to the increased level of
bandwidth such that only 50% is available for SVCs, you would enter 50% in the QoS
tab’s SVC Allowed (%) field (for the appropriate class of service) in the Add Logical
Port dialog box.
Note – A transit SPVC at a UNI or NNI endpoint is treated as an SVC and is subject
to the entered SVC allowed percentage. An originating or terminating SPVC at a UNI
or NNI endpoint is treated as a PVC and is not subject to the entered SVC allowed
percentage.
To Next Page
Loading...
