QoS and QoS Policies
26
Quality of Service Guide
3HE 11014 AAAC TQZZA Edition: 01
7705 SAR routers use QoS policies to control how QoS is handled at distinct points
in the service delivery model within the device. QoS policies act like a template. Once
a policy is created, it can be applied to many other similar services and ports. As an
example, if there is a group of Node Bs connected to a 7705 SAR node, one QoS
policy can be applied to all services of the same type, such as High-Speed Downlink
Packet Access (HSDPA) offload services.
There are different types of QoS policies that cater to the different QoS needs at each
point in the service delivery model. QoS policies are defined in a global context in the
7705 SAR and only take effect when the policy is applied to a relevant entity.
QoS policies are uniquely identified with a policy ID number or a policy ID name.
Policy ID 1 and policy ID “default” are reserved for the default policy, which is used
if no policy is explicitly applied.
The different QoS policies within the 7705 SAR can be divided into two main types.
• QoS policies are used for classification, queue attributes, and marking.
• Slope policies define default buffer allocations and Random Early Discard (RED)
and Weighted Random Early Discard (WRED) slope definitions.
The sections that follow provide an overview of the QoS traffic management
performed on the 7705 SAR.
3.1.2 Egress and Ingress Traffic Direction
Throughout this document, the terms ingress and egress, when describing traffic
direction, are always defined relative to the fabric. For example:
• ingress direction describes packets moving into the switch fabric away from a
port (on an adapter card)
• egress direction describes packets moving from the switch fabric and into a port
(on an adapter card)
When combined with the terms access and network, which are port and interface
modes, the four traffic directions relative to the fabric are (see Figure 1):
• access ingress direction describes packets coming in from customer equipment
and switched toward the switch fabric
• network egress direction describes packets switched from the switch fabric into
the network
• network ingress direction describes packets switched in from the network and
moving toward the switch fabric
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