Reference Guide

Congure priority to priority group mapping from priority 0 to priority 7 in order.
4. Exit the DCB MAP conguration mode.
DCB-MAP mode
exit
5. Enter interface conguration mode.
CONFIGURATION mode
interface type slot/port
6. Apply the dcb-map with PFC and ETS congurations to both ingress and egress interfaces.
INTERFACE mode
dcb-map map-name
7. Repeat steps 1 to 6 on all PFC and ETS enabled interfaces to ensure lossless trac service.
NOTE: All these congurations are available only in PMUX mode and you cannot perform these congurations in
Standalone mode.
Dell Networking OS Behavior: As soon as you apply a DCB MAPwith PFC enabled on an interface, DCBx starts exchanging
information with PFC-enabled peers. The IEEE802.1Qbb, CEE, and CIN versions of PFC Type, Length, Value (TLV) are supported.
DCBx also validates PFC congurations that are received in TLVs from peer devices.
By applying a DCB MAP with PFC enabled, you enable PFC operation on ingress port trac. To achieve complete lossless handling
of trac, also enable PFC on all DCB egress ports or congure the dot1p priority-queue assignment of PFC priorities to lossless
queues.
To remove a DCB MAP, including the PFC and ETS congurations it contains, use the no dcb-map map-name command in
INTERFACE Conguration mode.
You can enable any number of 802.1p priorities for PFC. Queues to which PFC priority trac is mapped are lossless by default. Trac
may be interrupted due to an interface ap (going down and coming up) when you recongure the lossless queues for no-drop
priorities in a PFC dcb-map and reapply the policy to an interface.
To apply PFC, a PFC peer must support the congured priority trac (as detected by DCBx).
To honor a PFC pause frame multiplied by the number of PFC-enabled ingress ports, the minimum link delay must be greater than
the round-trip transmission time the peer requres.
If you apply dcb-map with PFC disabled (no pfc mode on):
• You can enable link-level ow control on the interface. To delete the dcb-map, rst disable link-level ow control. PFC is then
automatically enabled on the interface because an interface is by default PFC-enabled.
• PFC still allows you to congure lossless queues on a port to ensure no-drop handling of lossless trac.
NOTE: You cannot enable PFC and link-level ow control at the same time on an interface.
When you apply a dcb-map to an interface, an error message displays if:
• The PFC dot1p priorities result in more than two lossless port queues globally on the switch.
• Link-level ow control is already enabled. You cannot be enable PFC and link-level ow control at the same time on an interface.
• In a switch stack, congure all stacked ports with the same PFC conguration.
A DCB MAP for PFC applied to an interface may become invalid if you recongure dot1p-queue mapping. This situation occurs when
the new dot1p-queue assignment exceeds the maximum number (2) of lossless queues supported globally on the switch. In this
case, all PFC congurations received from PFC-enabled peers are removed and resynchronized with the peer devices.
Trac may be interrupted when you recongure PFC no-drop priorities in a dcb-map or reapply the dcb-map to an interface.
Data Center Bridging (DCB)
33