DELL 8132 ユーザーズマニュアル

Priority Flow Control Commands

addition to the headroom.  With two no-drop priorities per interface and 

static allocations, there is only about 30 percent of the buffer space available 

for normal forwarding behavior.
The effective default behavior on an interface enabled for PFC without a no-

drop priority is that no flow control (legacy or PFC) is enabled.  If the user 

enables PFC but does not create any no-drop priorities, the interface will not 

be lossless.
Changing the drop and no-drop capabilities on an interface, either in flow 

control or priority flow control, may require that all ports briefly drop link.  

The priority to flow control group cannot be changed while traffic is running.  

When 802.3 link flow control is enabled, all priorities are mapped to a single 

flow control group.  When 802.1Qbb is enabled, the priorities are each 

mapped into their own flow control group, where lossless groups have 

additional buffer to handle the round trip delay for flow control.  In order to 

minimize the impact, the link will only be dropped when changing between 

802.3 and 802.1Qbb.

This chapter explains the following commands:

Use the priority-flow-control mode on command in Datacenter-Bridging 

Config mode to enable Priority-Flow-Control (PFC) on an interface. To 

disable Priority-Flow-Control, use the no form of the command.

priority-flow-control mode
priority-flow-control priority
clear priority-flow-control statistics
show interfaces priority-flow-control

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