Guaranteed minimum bandwidth operates in two different QoS enforcement contexts: Networking service backend enforcement and resource allocation scheduling enforcement.

When you use Network service backend enforcement, the network back end, ML2/OVN or ML2/SR-IOV, attempts to guarantee that each port on which the rule is applied has no less than the specified network bandwidth.

When you use resource allocation scheduling bandwidth enforcement, the Compute service (nova) places VM instances only on hosts that support the minimum bandwidth.

You can apply QoS minimum bandwidth rules by using Networking service back-end enforcement, resource allocation scheduling enforcement, or both.

The following table identifies the Modular Layer 2 (ML2) mechanism drivers that support minimum bandwidth QoS policies: