Objectives

Upon completing this lesson, you will be able to configure class-based shaping to rate-limit traffic. This ability includes being able to meet these objectives:

■ Explain the key features of class-based shaping

■ Explain how the two rate limits—average rate and peak rate—can be used to rate-limit traffic

■ Identify the Cisco IOS commands required to configure class-based shaping

■ Identify the Cisco IOS commands used to monitor class-based shaping

This topic describes the key features of class-based shaping.

This topic describes the key features of class-based shaping.

Central Site

PR/ATM WAN

Branch Office

Central Site

PR/ATM WAN

Bottleneck

CB Shaping with CBWFQ

Class Mission-Critical - Shape to 384 kbps

Min BW 256K Class Transactional - Shape to 192 kbps Min BW 128k

Bottleneck

Branch Office

CB Shaping with CBWFQ

Class Mission-Critical - Shape to 384 kbps

Min BW 256K Class Transactional - Shape to 192 kbps Min BW 128k

• Class-based shaping is used to rate-limit packets.

• Class-based shaping delays exceeding packets rather than dropping them.

• Class-based shaping has no marking capabilities.

• Class-based shaping is a version of GTS using MQC.

Traffic shaping allows you to control the traffic going out from an interface in order to match its transmission speed to the speed of the remote, target interface, and to ensure that the traffic conforms to policies contracted for it. You can shape traffic adhering to a particular profile to meet downstream requirements, thereby eliminating bottlenecks in topologies with traffic-rate mismatches or oversubscriptions. Class-based shaping has these properties:

■ Class-based shaping, a version of Generic Traffic Shaping (GTS), is configured via MQC.

■ Class-based shaping has no packet-marking capabilities.

■ Class-based shaping works by queuing exceeding packets until the packets conform to the configured shaped rate.

■ Class-based shaping can also be used within the class-based weighted fair queuing (CBWFQ) queuing system. When operating within CBWFQ, the shaped rate provides an upper bandwidth limit while the bandwidth statement within CBWFQ provides a minimum bandwidth guarantee.

This topic describes how the two rate limits—average rate and peak rate—can be used to ratelimit traffic.

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