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Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software
How to Configure QoS Congestion Management on Cisco IOS XR Software
QC-37
Cisco IOS XR Modular Quality of Service Configuration Guide
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.
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.
Table 3 Differences Between Traffic Shaping and Traffic Policing
Traffic Shaping Traffic Policing
Triggering Event
• Occurs automatically at regular intervals
(Tc).
or
Occurs whenever a packet arrives at an
interface.
• Occurs whenever a packet arrives at an
interface.
What it Does
• Classifies packets.
• If a packet does not meet match criteria, no
further action is taken.
• Packets meeting match criteria are sent (if
there are enough tokens in the token bucket)
or
Packets are placed in a queue for
transmission later.
• If the number of packets in the queue exceed
the queue limit, the packets are dropped.
• Classifies packets.
• If packet does not meet match criteria,
no further action is taken.
• Packets meeting match criteria and
conforming to or exceeding a specified
rate, receive the configured policing
action (for example, drop, send, mark,
then send).
• Packets are not placed in a queue for
transmission later.