Users Guide

CONFIGURATION mode

interface type slot/port

8. Apply the input policy with the PFC configuration to an ingress interface.

INTERFACE mode

dcb-policy input policy-name

9. Repeat Steps 1 to 8 on all PFC-enabled peer interfaces to ensure lossless traffic service.

Dell Networking OS Behavior: As soon as you apply a DCB policy with 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 configurations that are received

in TLVs from peer devices.

By applying a DCB input policy with PFC enabled, you enable PFC operation on ingress port traffic. To

achieve complete lossless handling of traffic, also enable PFC on all DCB egress ports or configure the

dot1p priority-queue assignment of PFC priorities to lossless queues.

To remove a DCB input policy, including the PFC configuration it contains, use the no dcb-input

policy-name

command in INTERFACE Configuration mode. To disable PFC operation on an interface,

use the no pfc mode on command in DCB Input Policy Configuration mode. PFC is enabled and

disabled as the global DCB operation is enabled (

dcb enable) or disabled (no dcb enable).

You can enable any number of 802.1p priorities for PFC. Queues to which PFC priority traffic is mapped

are lossless by default. Traffic may be interrupted due to an interface flap (going down and coming up)

when you reconfigure the lossless queues for no-drop priorities in a PFC input policy and reapply the

policy to an interface.

To apply PFC, a PFC peer must support the configured priority traffic (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 an input policy with PFC disabled (no pfc mode on):

• You can enable link-level flow control on the interface. To delete the input policy, first disable link-

level flow control. PFC is then automatically enabled on the interface because an interface is by

default PFC-enabled.

• PFC still allows you to configure lossless queues on a port to ensure no-drop handling of lossless

traffic.

NOTE: You cannot enable PFC and link-level flow control at the same time on an interface.

When you apply an input policy 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 flow control is already enabled. You cannot be enable PFC and link-level flow control at the

same time on an interface.

• In a switch stack, configure all stacked ports with the same PFC configuration.

A DCB input policy for PFC applied to an interface may become invalid if you reconfigure 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 configurations received from

PFC-enabled peers are removed and resynchronized with the peer devices.

Data Center Bridging (DCB)