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 |
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| Traffic Shaping | Traffic Policing |
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Triggering Event | • Occurs automatically at regular intervals | • Occurs whenever a packet arrives at an | |
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| (Tc). | interface. |
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| or |
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| Occurs whenever a packet arrives at an |
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| interface. |
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What it Does | • Classifies packets. | • Classifies packets. | |
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| • If a packet does not meet match criteria, no | • If packet does not meet match criteria, |
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| further action is taken. | no further action is taken. |
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| • Packets meeting match criteria are sent (if | • Packets meeting match criteria and |
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| there are enough tokens in the token bucket) | conforming to or exceeding a specified |
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| or | rate, receive the configured policing |
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| action (for example, drop, send, mark, | |
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| Packets are placed in a queue for | |
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| then send). | |
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| transmission later. | • Packets are not placed in a queue for |
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| • If the number of packets in the queue exceed | |
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| transmission later. | |
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| the queue limit, the packets are dropped. |
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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
•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