7

Configuring Quality of Service

This section provides information for defining and configuring Quality of Service (QoS) parameters.

Quality of Service (QoS) Overview

An implementation example that requires QoS includes certain types of traffic such as Voice, Video, and real-time traffic, which 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. The system supports four queues per port. After a packet is classified, it assigned to one of the output queues. QoS Terms:

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 packets being forwarded are based on packet information and packet field values, such as VLAN priority (VPT) and DSCP (DiffServ Code Point).

VPT Tag Classification Information

VLAN Priority Tags are used to classify the packets by mapping packets to one of the egress queues. VLAN Priority Tag to queue assignments are user-definable. The table below details the VPT to queue default settings:

Table 7-1. VPT to Queue Default Settings

CoS Value

Forwarding Queue Values

 

 

 

0

q2

(Best Effort)

 

 

 

1

q1

(Lowest Priority)

 

 

 

2

q1

(Lowest Priority)

 

 

 

3

q2

(Best Effort)

 

 

 

4

q3

 

 

 

 

5

q3

 

 

 

 

6

q4

(Highest Priority)

 

 

 

7

q4

(Highest Priority)

 

 

 

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Dell PC2708, PC2748 Configuring Quality of Service, Quality of Service QoS Overview, VPT Tag Classification Information