Cisco ASA Series User Manual

CHAPTER
1-1
Cisco ASA Series CLI Configuration Guide
1
Configuring QoS
Have you ever participated in a long-distance phone call that involved a satellite connection? The
conversation might be interrupted with brief, but perceptible, gaps at odd intervals. Those gaps are the
time, called the latency, between the arrival of packets being transmitted over the network. Some network
traffic, such as voice and video, cannot tolerate long latency times. Quality of service (QoS) is a feature
that lets you give priority to critical traffic, prevent bandwidth hogging, and manage network bottlenecks
to prevent packet drops.
Note For the ASASM, we suggest performing QoS on the switch instead of the ASASM. Switches have more
capability in this area.
This chapter describes how to apply QoS policies and includes the following sections:
• Information About QoS, page 1-1
• Licensing Requirements for QoS, page 1-5
• Guidelines and Limitations, page 1-5
• Configuring QoS, page 1-6
• Monitoring QoS, page 1-16
• Feature History for QoS, page 1-19
Information About QoS
You should consider that in an ever-changing network environment, QoS is not a one-time deployment,
but an ongoing, essential part of network design.
This section describes the QoS features supported by the ASA and includes the following topics:
• Supported QoS Features, page 1-2
• What is a Token Bucket?, page 1-2
• Information About Policing, page 1-3
• Information About Priority Queuing, page 1-3
• Information About Traffic Shaping, page 1-4
• DSCP and DiffServ Preservation, page 1-5

Cisco ASA Series Specifications

General

Brand	Cisco
Model	ASA Series
Category	Network Hardware
Language	English