Configuring Quality of Service
Quality of Service
(QoS) provides the ability to implement QoS and priority queuing within a network. For example, certain types of traffic that
require minimal delay, such as Voice, Video, and real-time traffic can be assigned a high priority queue, while other traffic can be assigned a lower
priority queue. The result is an improved traffic flow for traffic with high demand. QoS is defined by:
•
Classification
— Specifies which packet fields are matched to specific values. All packets matching the user-defined specifications are
classified together.
•
Action
— Defines traffic management where packet forwarding is based on packet information and packet field values such as
VLAN Priority
Tag
(VPT) and
DiffServ Code Point
(DSCP).
After packets are assigned to a specific egress queue, CoS services can be assigned to the queue. Egress queues are configured with a
scheduling scheme by one of the following methods:
•
Strict Priority
— Ensures that time-sensitive applications are always forwarded. Strict Priority (SP) allows the prioritization of mission-critical,
time-sensitive traffic over less time-sensitive applications.
For example, under SP, voice over IP (VoIP) traffic can be prioritized so that it is forwarded before FTP or email (SMTP) traffic.
•
Weighted Round Robin
— Ensures that a single application does not dominate the device forwarding capacity. Weighted Round Robin
(WRR) forwards entire queues in a round robin order. All queues can participate in WRR, except SP queues. If the traffic flow is minimal, and
SP queues do not occupy the whole bandwidth allocated to a port, the WRR queues can share the bandwidth with the SP queues. This
ensures that the remaining bandwidth is distributed according to the weight ratio. If WRR is selected, the following weights are assigned to the
queues: 1, 2, 4, 8.
This section contains information for defining general QoS settings, and includes the following topics:
•
Defining General QoS Setting
•
Defining QoS Queues
•
Configuring Bandwidth Settings
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