Traffic Shaping

An even more proactive approach to handling traffic is traffic shaping . By using traffic shaping, we can ensure a certain amount of bandwidth for certain traffic. With the shape command, we can assign a CIR value, which is the committed information rate in bits per second.

Some optional keywords for the shape command are average, peak, bc-value, and be-value. Table 11-9 lists keywords for this command.

 shape {average  | peak } cir-value  [bc-value ] [be-value ]

Table 11-9. Shape command keywords

Shape keyword



Specifies the average rate, which ensures an expected bandwidth.


Specifies the peak rate, which allows the traffic to peak to if there is enough bandwidth available.


The committed information rate in bits per second, which is used to define our average or peak values.


The committed burst size, in bits.


The excess burst size, in bits.


11.6.1. Traffic Shaping Example

In this example , we attempt to ensure that our traffic can have at least 300 Kbps, but we are going to allow it to peak to 512 Kbps if there is enough bandwidth available on the interface.

 policy-map policy1
 class premium
 bandwidth 300
 shape peak 512000


11.6.2. Frame-Relay Shaping

For frame-relay, we can apply traffic shaping commands directly to the interface with the command traffic-shape. For more information and examples, see Chapter 6.

Getting Started

IOS Images and Configuration Files

Basic Router Configuration

Line Commands

Interface Commands

Networking Technologies

Access Lists

IP Routing Topics

Interior Routing Protocols

Border Gateway Protocol

Quality of Service

Dial-on-Demand Routing

Specialized Networking Topics

Switches and VLANs

Router Security

Troubleshooting and Logging

Quick Reference

Appendix A Network Basics


Cisco IOS in a Nutshell
Cisco IOS in a Nutshell (In a Nutshell (OReilly))
ISBN: 0596008694
EAN: 2147483647
Year: 2006
Pages: 1031
Authors: James Boney © 2008-2020.
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