QoS Policies
40 Quality of Service Guide
Service versus Network QoS
The QoS mechanisms within the routers are specialized for the type of traffic on the interface.
For customer interfaces, there is service ingress and egress traffic, and for network core
interfaces, there is network ingress and network egress traffic, as shown in Figure 3.
Figure 3: Service vs Network Traffic Types
The router uses QoS policies applied to a SAP for a service or to a network MDA/port to
define the queuing, queue attributes, and QoS marking/interpretation.
Scheduler Customer multi-
service site
Service SAP
• Defines the hierarchy and parameters for each
scheduler
• Defined in the context of a tier which is used to
place the scheduler within the hierarchy
• Three tiers of virtual schedulers are supported
Scheduler
Policies
Shared Queue SAP ingress • Shared-queues can be implemented to mitigate
the queue consumption on an MDA
Shared
Queues
ATM Traffic
Descriptor
Profile
SAP ingress • Defines the expected rates and characteristics
of traffic. Specified traffic parameters are used
for policing ATM cells and for selecting the
service category for the per-VC queue
ATM
Traffic
Descriptor
Profiles
ATM Traffic
Descriptor
Profile
SAP egress • Specified traffic parameters are used for
scheduling and shaping ATM cells and for
selecting the service category for the per-VC
queue
ATM
Traffic
Descriptor
Profiles
Table 4: QoS Policy Types and Descriptions (Continued)
Policy Type Applied at… Description Page
OSSG019
Access Network
Network Egress
Network Ingress
Service Ingress
Router
Service Egress
Switch Fabric
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