Users Guide

Step Task Command Command Mode
Dell# interface tengigabitEthernet 1/1/1
Dell(config-if-te-1/1/1)# dcb-map
SAN_A_dcb_map1 Repeat Steps 1 and 2 to apply a DCB map
to more than one port.
You cannot apply a DCB map on an interface that has been
already congured for PFC using thepfc priority
command or which is already congured for lossless queues
(pfc no-drop queues command).
Conguring PFC without a DCB Map
In a network topology that uses the default ETS bandwidth allocation (assigns equal bandwidth to each priority), you can also enable PFC
for specic dot1p-priorities on individual interfaces without using a DCB map. This type of DCB conguration is useful on interfaces that
require PFC for lossless trac, but do not transmit converged Ethernet trac.
Table 16. Conguring PFC without a DCB Map
Step Task Command Command Mode
1 Enter interface conguration mode on an Ethernet port.
interface {tengigabitEthernet
slot/port |
fortygigabitEthernet slot/port}
CONFIGURATION
2 Enable PFC on specied priorities. Range: 0-7. Default:
None.
Maximum number of lossless queues supported on an
Ethernet port: 2.
Separate priority values with a comma. Specify a priority
range with a dash, for example: pfc priority 3,5-7
1 You cannot congure PFC using the pfc priority
command on an interface on which a DCB map has
been applied or which is already congured for lossless
queues (pfc no-drop queues command).
pfc priority priority-
range
INTERFACE
Priority-Based Flow Control Using Dynamic Buer
Method
In a data center network, priority-based ow control (PFC) manages large bursts of one trac type in multiprotocol links so that it does not
aect other trac types and no frames are lost due to congestion. When PFC detects congestion on a queue for a specied priority, it
sends a pause frame for the 802.1p priority trac to the transmitting device.
Pause and Resume of Trac
The pause message is used by the sending device to inform the receiving device about a congested, heavily-loaded trac state that has
been identied. When the interface of a sending device transmits a pause frame, the recipient acknowledges this frame by temporarily
halting the transmission of data packets. The sending device requests the recipient to restart the transmission of data trac when the
congestion eases and reduces. The time period that is specied in the pause frame denes the duration for which the ow of data packets
is halted. When the time period elapses, the transmission restarts.
256
Data Center Bridging (DCB)