Dell Force10 MXL Blade Configuration Manual page 123

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 received in TLVs from peer devices.
If you reocnfigure the PFC priorities in an input policy and re-apply
the policy to an interface,
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 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 or
disabled as 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
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 needs to honor PFC pause frame by
peer multiplied by the number of PFC-enabled ingress ports.
If you apply an input policy with PFC disabled (no pfc mode on):
- Link-level flow control can be enabled on the interface (refer to
Pause Frames on page
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.
A DCB input policy for PFC applied to an interface may become invalid if dot1p-queue mapping is
reconfigured (refer to
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 re-synchronized
with the peer devices.
Traffic may be interrupted when you reconfigure PFC no-drop priorities in an input policy or re-apply
the policy to an interface.
FTOS does not support MACsec Bypass Capability (MBC).
Queues).
247). To delete the input policy, you must first disable link-level flow control.
Configuring Lossless Queues).
Create Input Policy
Layer 2 Flow Control Using Ethernet
Maps). This situation occurs when the new dot1p-queue
Data Center Bridging (DCB) | 121