Licensing Requirements; Prerequisites For Priority Flow Control; Guidelines And Limitations - Cisco Nexus 7000 Series Configuration Manual

Licensing Requirements

required for transmitting 512 bits at the speed of the port. The range is from 0 to 65535. A pause frame with
a pause quanta of 0 indicates a resume frame to restart the paused traffic.
Note
Only certain classes of service of traffic can be flow controlled while other classes are allowed to operate
normally.
PFC asks the peer to stop sending frames of a particular CoS value by sending a pause frame to a well-known
multicast address. This pause frame is a one-hop frame that is not forwarded when received by the peer. When
the congestion is mitigated, PFC can request the peer to restart transmitting frames.
Licensing Requirements
The QoS feature does not a require license. Any feature not included in a license package is bundled with the
Cisco NX-OS system images and is provided at no extra charge to you.
Using virtual device contexts (VDCs) requires an Advanced Services license.
For a complete explanation of the Cisco NX-OS licensing scheme, see the Cisco NX-OS Licensing Guide.

Prerequisites for Priority Flow Control

PFC has the following prerequisites:
• You must be familiar with "Using Modular QoS CLI."
• You are logged on to the switch.
• You are in the VDC. A VDC is a logical representation of a set of system resources. You can use the

Guidelines and Limitations

PFC has the following configuration guidelines and limitations:
• If PFC is enabled on a port or a port channel, it does not cause a port flap.
• A flap occurs when both the PFC and LFC are enabled and PFC is disabled before LFC is configured.
• PFC configuration enables PFC in both the send (Tx) and receive (Rx) direction.
• PFC on mode is used to support the hosts that support PFC but do not support the Data Center Bridging
• Only an exact match of the no-drop CoS is considered as a successful negotiation of PFC by the DCBXP.
• M3 modules do not support Priority Flow Control.
Cisco Nexus 7000 Series NX-OS Quality of Service Configuration Guide
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switchto vdc command with a VDC number.
Capability Exchange Protocol (DCBXP).
Configuring Priority Flow Control