QoS Bandwidth Management

QoS bandwidth management allows you to control traffic flows on a network so that traffic does not exceed network capacity (resulting in network congestion) and also allows you to allocate bandwidth for certain types of traffic and for applications and users. With QoS, you can enforce bandwidth for traffic on a narrow or a broad scale. A QoS profile rule allows you to set bandwidth limits for individual QoS classes and the total combined bandwidth for all eight QoS classes. As part of the steps to Configure QoS, you can attach the QoS profile rule to a physical interface to enforce bandwidth settings on the traffic exiting that interface—the individual QoS class settings are enforced for traffic matching that QoS class (QoS classes are assigned to traffic matching QoS Policy rules) and the overall bandwidth limit for the profile can be applied to all clear text traffic, specific clear text traffic originating from source interfaces and source subnets, all tunneled traffic, and individual tunnel interfaces. You can add multiple profile rules to a single QoS interface to apply varying bandwidth settings to the traffic exiting that interface.
The following fields support QoS bandwidth settings:
  • Egress Guaranteed—The amount of bandwidth guaranteed for matching traffic. When the egress guaranteed bandwidth is exceeded, the firewall passes traffic on a best-effort basis. Bandwidth that is guaranteed but is unused continues to remain available for all traffic. Depending on your QoS configuration, you can guarantee bandwidth for a single QoS class, for all or some clear text traffic, and for all or some tunneled traffic.
    Example:
    Class 1 traffic has 5 Gbps of egress guaranteed bandwidth, which means that 5 Gbps is available but is not reserved for class 1 traffic. If Class 1 traffic does not use or only partially uses the guaranteed bandwidth, the remaining bandwidth can be used by other classes of traffic. However, during high traffic periods, 5 Gbps of bandwidth is absolutely available for class 1 traffic. During these periods of congestion, any Class 1 traffic that exceeds 5 Gbps is best effort.
  • Egress Max—The overall bandwidth allocation for matching traffic. The firewall drops traffic that exceeds the egress max limit that you set. Depending on your QoS configuration, you can set a maximum bandwidth limit for a QoS class, for all or some clear text traffic, for all or some tunneled traffic, and for all traffic exiting the QoS interface.
    The cumulative guaranteed bandwidth for the QoS profile rules attached to the interface must not exceed the total bandwidth allocated to the interface.
To define bandwidth settings for QoS classes, see Step Add a QoS profile rule. To then apply those bandwidth settings to clear text and tunneled traffic, and to set the overall bandwidth limit for a QoS interface, see Step Enable QoS on a physical interface.

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