Dell PowerConnect 8024 User Configuration Manual page 809

PFC Operation and Behavior
PFC uses a new control packet defined in IEEE 802.1Qbb and therefore is
not compatible with IEEE 802.3 Annex 31B flow control. An interface that is
configured for PFC will be automatically disabled for flow control. When
PFC is disabled on an interface, the flow control configuration for the
interface becomes active. Any flow control frames received on a PFC
configured interface are ignored.
Each priority is configured as either
designated as no-drop is congested, the priority is paused. Drop priorities do
not participate in pause. You must configure the same no-drop priorities
across the network in order to ensure end-to-end lossless behavior.
Operator configuration of PFC is used only when the port is configured in a
manual role. When interoperating with other equipment in a manual role,
the peer equipment must be configured with identical PFC priorities and
VLAN assignments. Interfaces not enabled for PFC ignore received PFC
frames. Ports configured in auto-upstream or auto-downstream roles receive
their PFC configuration from the configuration source and ignore any
manually-configured information.
NOTE:
This feature is configurable on physical full duplex interfaces only. To
enable PFC on a LAG interface, the member interfaces must have the same
configuration.
When PFC is disabled, the interface defaults to the IEEE 802.3 flow control
setting for the interface. PFC is disabled by default.
If you enable priority-based flow control for a particular priority value on an
interface, ensure that Voice VLAN tagging is enabled on the interface so that
the 802.1p priority values are carried through the network (see "Voice VLAN"
on page 563). Additionally, make sure 802.1p priority values are mapped to
CoS values (see "Configuring Class-of-Service" on page 1105).
drop no-drop
or . If a priority that is
Configuring Data Center Features
809