5-1 
 
z  The models listed in this document are not applicable to all regions. Please consult your local sales 
office for the models applicable to your region. 
z  Support of the H3C WA series WLAN access points (APs) for features may vary by AP model. For 
more information, see Feature Matrix.  
z  The interface types and the number of interfaces vary by AP model.  
z  The term AP in this document refers to common APs, wireless bridges, and mesh APs. 
 
5  QoS Overview 
This chapter includes these sections: 
z  Introduction to QoS 
z  Introduction to QoS Service Models 
z  QoS Techniques Overview 
Introduction to QoS 
In data communications, Quality of Service (QoS) is the ability of a network to provide differentiated 
service guarantees for diversified traffic in terms of bandwidth, delay, jitter, and drop rate.  
Network resources are always scarce. The contention for resources demands that QoS prioritize 
important traffic flows over trivial traffic flows. When making a QoS scheme, a network administrator 
must consider the characteristics of various applications to balance the interests of diversified users 
and fully utilize network resources.  
The subsequent section describes some typical QoS service models and widely-used mature QoS 
techniques. By appropriately using these techniques, you can improve QoS effectively.  
Introduction to QoS Service Models 
This section covers three typical QoS service models:  
z  Best-Effort Service Model 
z  IntServ Service Model 
z  DiffServ Service Model 
Best-Effort Service Model 
Best effort is a single service model and also the simplest service model. In the best effort service model, 
the network does its best to deliver packets but does not guarantee delay or reliability.  
The best-effort service model is the default model in the Internet and applies to most network 
applications. It uses the first in first out (FIFO) queuing mechanism.