Dell Force10 S4810P Configuration Manual page 310

FTOS 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 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, you must also enable PFC on all DCB egress ports or
configure the dot1p priority-queue assignment of PFC priorities to lossless queues (refer to
Configuring Lossless
To remove a DCB input policy, including the PFC configuration it contains, use the
policy-name
use the
disabled as the global DCB operation is enabled (
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
re-apply the policy to an interface.
For PFC to be applied, the configured priority traffic must be supported by a PFC peer (as detected by
DCBx).
To honor a PFC pause frame multiplied by the number of PFC-enabled ingress ports, the minimum
link delay should be greater than the round-trip transmission time required by a peer.
If you apply an input policy with PFC disabled (
- Link-level flow control can be enabled on the interface (refer to
To delete the input policy, you must 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 (refer to
PFC and link-level flow control cannot be enabled at the same time on an interface.
When you apply an input policy to an interface, an error message is displayed if:
- The PFC dot1p priorities result in more than two lossless port queues globally on the switch.
- Link-level flow control is already enabled. PFC and link-level flow control cannot be enabled at the
same time on an interface.
- In a switch stack, you must configure all stacked ports with the same PFC configuration.
310
| Data Center Bridging (DCB)
Queues).
command in INTERFACE Configuration mode. To disable PFC operation on an interface,
command in DCB Input Policy Configuration mode. PFC is enabled and
no pfc mode on
Configuring Lossless
) or disabled (
dcb enable
no pfc mode on
Queues).
no dcb-input
).
no dcb enable
):
Ethernet Pause Frames on page 469).