Cisco Systems QC-29 manual Traffic Shaping Versus Traffic Policing, QC-37

Models: QC-29

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Traffic Shaping Versus Traffic Policing

Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software

How to Configure QoS Congestion Management on Cisco IOS XR Software

Traffic Shaping Versus Traffic Policing

Although traffic shaping and traffic policing can be implemented together on the same network, there are distinct differences between them, as shown in Table 3.

Table 3

Differences Between Traffic Shaping and Traffic Policing

 

 

 

 

 

 

 

Traffic Shaping

Traffic Policing

 

 

 

Triggering Event

Occurs automatically at regular intervals

Occurs whenever a packet arrives at an

 

 

(Tc).

interface.

 

 

or

 

 

 

Occurs whenever a packet arrives at an

 

 

 

interface.

 

 

 

 

What it Does

Classifies packets.

Classifies packets.

 

 

If a packet does not meet match criteria, no

If packet does not meet match criteria,

 

 

further action is taken.

no further action is taken.

 

 

Packets meeting match criteria are sent (if

Packets meeting match criteria and

 

 

there are enough tokens in the token bucket)

conforming to or exceeding a specified

 

 

or

rate, receive the configured policing

 

 

action (for example, drop, send, mark,

 

 

Packets are placed in a queue for

 

 

then send).

 

 

transmission later.

Packets are not placed in a queue for

 

 

If the number of packets in the queue exceed

 

 

transmission later.

 

 

the queue limit, the packets are dropped.

 

 

 

 

 

How to Configure QoS Congestion Management on Cisco IOS XR Software

This section contains instructions for the following tasks:

Configuring Guaranteed and Remaining Bandwidths, page QC-37(required)

Configuring Low-Latency Queueing with Strict Priority Queueing, page QC-40(required)

Configuring Traffic Shaping, page QC-42(required)

Configuring Traffic Policing, page QC-45(required)

Configuring Guaranteed and Remaining Bandwidths

The bandwidth command allows you to specify the exact amount of bandwidth to be allocated for a specific class of traffic. MDRR is implemented as the scheduling algorithm.

The bandwidth remaining command specifies a weight for the class to the MDRR. The MDRR algorithm derives the weight for each class from the bandwidth remaining value allocated to the class. If you do not configure the bandwidth remaining command for any class, the leftover bandwidth is allocated equally to all classes.

Cisco IOS XR Modular Quality of Service Configuration Guide

QC-37

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Cisco Systems QC-29 manual Traffic Shaping Versus Traffic Policing, Configuring Guaranteed and Remaining Bandwidths, QC-37