Bandwidth And Priority Service - Cisco 10000 Series Configuration Manual

Chapter 5 Distributing Bandwidth Between Queues

Bandwidth and Priority Service

To configure priority queuing, use the priority command in policy-map class configuration mode and
configure the bandwidth in the following way:
•
•
When you create a priority queue using the priority command, the router sets the committed information
rate (CIR) of the queue to near link bandwidth. Therefore, the priority queue can consume almost all of
the link bandwidth when packets are transmitted from it. As a result, there is no way to guarantee
bandwidth to the other queues on the link. To resolve this, configure the other queues using the
bandwidth remaining command. This command enables the router to allocate relative amounts of
bandwidth, eliminating the need to constantly change the class bandwidth.
Table 5-4
Table 5-4
Function
Minimum bandwidth guarantee
Maximum bandwidth guarantee
Built-in policer
Provides low-latency
The bandwidth and priority commands are also designed to meet different QoS policy objectives.
Table 5-5
Table 5-5
Application
Bandwidth management for WAN links
Manage delay and variations in delay (jitter)
Improve application response time
OL-7433-09
In releases prior to Cisco IOS Release 12.3(7)XI, specify a minimum bandwidth rate using the
priority command.
In Cisco IOS Release 12.3(7)XI and later releases, specify a minimum bandwidth rate using the
police command. The router no longer supports the percent and bandwidth-kbps options for the
priority command.
lists the functional differences between the bandwidth and priority commands:
Comparison of Functional Differences Between the bandwidth and priority
Commands
lists those differing objectives:
Comparison of QoS Policy Objectives of the bandwidth and priority Commands
bandwidth Command
Yes
No
No
No
bandwidth Command
Yes
No
No
Cisco 10000 Series Router Quality of Service Configuration Guide
Bandwidth Distribution Between Queues
priority Command
Yes
Yes
No
Yes
priority Command
Somewhat
Yes
Yes
5-7