3com 2948-SFP Plus User Guide

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 packets are  

 

forwarded are based on packet information, and packet field values  

 

such as VLAN Priority Tag (VPT) and DiffServ Code Point (DSCP). 

 

VPT Classification Information — VLAN Priority Tags (VPT)  

 

are used to classify packets by mapping packets to one of the  

 

egress queues. VPT to Queue assignments are user-definable.  

 

Packets arriving untagged are assigned a default VPT value, which is  

 

set on a per-port basis. The assigned VPT is used to map the packet  

 

to the egress queue. 

This section contains information for configuring QoS, and includes the 
following topics: 

  Viewing CoS Settings 
  Defining CoS 
  Defining Queuing Algorithm
  Viewing CoS to Queue 
  Defining CoS to Queue 
  Viewing DSCP to CoS 
  Configuring DSCP to CoS 
  Configuring Trust Settings 
  Viewing Bandwidth Settings 
  Defining Bandwidth Settings 
  Defining Voice VLAN