Examples of abnormal configuration scenarios.
If you attempt to configure PFC on a port that does not support it, an error message similar to the following is issued and you will be informed that PFC cannot be configured on that port:
BD8810.1# enable flow-control tx-pause priority 3 port 1:1 Error: Port 1:1 does not support Priority Flow Control.
If you attempt to configure PFC on a port in a system that has older MSM models, the PFC configuration will succeed as long as the user port supports it, but a log message will be issued indicating that overall PFC operation is not optimal.
01/22/2010 14:14:37.88 <Warn:HAL.VLAN.PFCSubopt> MSM-A: Priority Flow Control is enabled but system behavior will not be optimal. Older modules in the system cannot be programmed for fabric flow control.
When PFC is enabled on a port, IEEE 802.3x will be disabled. If, after enabling PFC, you try to modify RX or TX pause parameters, an error message similar to the following will be issued explaining the dependency on PFC configuration:
BD8810.1# enable flow-control tx-pause port 1:1 Error: Priority Flow Control is currently enabled on port 1:1 and is mutually exclusive with TX and RX pause configuration. TX and RX pause configuration cannot be done until PFC is disabled on this port.
If you try to configure PFC on older BlackDiamond 8900-10G24X-c modules that do not support PFC.
If a BlackDiamond 8900-10G24X-c module that supports PFC is replaced with a version that does not support PFC.
If a slot is preconfigured as an 8900-10G24X-c module, PFC is configured, and a version of the module that does not support PFC is inserted.
Under any of these conditions, the scenario is flagged and the following log message is issued to alert you to the misconfiguration:
01/22/2010 14:14:37.88 <Warn:HAL.VLAN.PFCUnsuprt> MSM-A: Port 4:1 is on an older model of the 8900-10G24X-c and does not support Priority Flow Control. 8900-10G24X-c 41632B, and VIM-10G8X 17012B are new models that support PFC.
If you try to configure PFC on a port in a SummitStack before you have configured the SummitStack for enhanced mode, the following error message is issued:
Slot-1 Stack.7 # enable flow-control rx-pause qosprofile qp1 port 1:1 Error: The stack is not configured for enhanced stacking mode. Issue the command "configure stacking protocol enhanced" to enable this mode and retry the PFC configuration.
On Summit X670 and X670V switches, if you try to configure PFC on alternate stack ports or SummitStack-V80 native stack ports, the following error message is issued:
07/18/2011 10:42:07.60 <Warn:HAL.Port.FabFlowCtrlUnsuprt> Slot-1: Slot 3 does not support fabric flow control messages on alternate stack ports or V80 native stack ports.