Install Guide

● All 802.1p priorities mapped to the same queue must be in the same priority group.
● A maximum of two PFC-enabled, lossless queues are supported on an interface.
Otherwise, the reconfiguration of a default dot1p-queue assignment is rejected.
● To ensure complete no-drop service, apply the same PFC parameters on all PFC-enabled peers.
PFC Prerequisites and Restrictions
On a switch, PFC is globally enabled by default, but not applied on specific 802.1p priorities. To enable PFC on 802.1p priorities,
create a DCB map.
The following prerequisites and restrictions apply when you configure PFC in a DCB map:
● You can enable PFC on a maximum of four priority queues on an interface. The default is two. Enabling PFC for dot1p
priorities configures the corresponding port queue as lossless.
● You cannot enable PFC and link-level flow control at the same time on an interface.
Applying a DCB Map on a Port
When you apply a DCB map with PFC enabled on a switch interface, a memory buffer for PFC-enabled priority traffic is
automatically allocated. The buffer size is allocated according to the number of PFC-enabled priorities in the assigned map.
To apply a DCB map to an Ethernet port, follow these steps:
Table 16. DCB Map to an Ethernet Port
Step Task Command Command Mode
1
Enter interface configuration mode on an Ethernet port.
interface interface-
type }
CONFIGURATION
2
Apply the DCB map on the Ethernet port to configure it
with the PFC and ETS settings in the map; for example:
DellEMC# interface tengigabitEthernet
1/1
DellEMC(config-if-te-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 configured for PFC using the pfc
priority command or which is already configured for
lossless queues (pfc no-drop queues command).
dcb-map name
INTERFACE
Configuring 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 specific dot1p-priorities on individual interfaces without using a DCB map. This type of DCB configuration is
useful on interfaces that require PFC for lossless traffic, but do not transmit converged Ethernet traffic.
Table 17. Configuring PFC without a DCB Map
Step Task Command Command Mode
1 Enter interface configuration mode on an Ethernet
port.
interface interface-
type}
CONFIGURATION
Data Center Bridging (DCB) 219