Chapter 18: Quality of Service (QoS) (CLI)
Configuring Scheduling (CLI)
phn-3963_004v000
Page 18-364
Configuring Scheduling (CLI)
This section includes:
Overview of Egress Scheduling (CLI)
Configuring Queue Priority (CLI)
Configuring Interface Priority Profiles (CLI)
Attaching a Priority Profile to an Interface (CLI)
Configuring Weighted Fair Queuing (WFQ) (CLI)
Overview of Egress Scheduling (CLI)
Egress scheduling is responsible for transmission from the priority queues. PTP 820 uses a unique
algorithm with a hierarchical scheduling model over the three levels of the egress path that
enables compliance with SLA requirements.
The scheduler scans all the queues over all the service bundles, per interface, and determines
which queue is ready to transmit. If more than one queue is ready to transmit, the scheduler
determines which queue transmits first based on:
Queue Priority – A queue with higher priority is served before lower-priority queues.
Weighted Fair Queuing (WFQ) – If two or more queues have the same priority and are ready to
transmit, the scheduler transmits frames from the queues based on a WFQ algorithm that
determines the ratio of frames per queue based on a predefined weight assigned to each
queue.
Configuring Queue Priority (CLI)
A priority profile defines the exact order for serving the eight priority queues in a single service
bundle. When you attach a priority profile to an interface, all the service bundles under the
interface inherit the profile.
The priority mechanism distinguishes between two states of the service bundle:
Green State – Committed state
Yellow state – Best effort state
Green State refers to any time when the service bundle rate is below the user-defined CIR. Yellow
State refers to any time when the service bundle is above the user-defined CIR but below the PIR.
You can define up to four Green priority profiles, from 4 (highest) to 1 (lowest). An additional four
Yellow priority profiles are defined automatically and cannot be changed or edited.
The following table provides a sample of an interface priority profile. This profile is also used as
the default interface priority profile.