Users Guide

• Dell Networking OS allows you to change the default dot1p priority-queue assignments only if the change satisfies the
following requirements in DCB maps already applied to the interfaces:
• 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 two priority queues on an interface. 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 14. DCB Map to an Ethernet Port
Step Task Command Command Mode
1
Enter interface configuration mode on an Ethernet port.
interface
{tengigabitEthernet slot/
port /subport |
fortygigabitEthernetslot/
port}
CONFIGURATION
2
Apply the DCB map on the Ethernet port to configure it
with the PFC and ETS settings in the map; for example:
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 configured for PFC using thepfc
priority
command or which is already configured for
lossless queues (pfc no-drop queues command).
dcb-map name
INTERFACE
Data Center Bridging (DCB) 231