Lossless traffic egresses out the no-drop queues. Ingress dot1p traffic from PFC-enabled interfaces is
automatically mapped to the no-drop egress queues.
1. Enter INTERFACE Configuration mode.
CONFIGURATION mode
interface type slot/port/subport
2. Configure the port queues that will still function as no-drop queues for lossless traffic.
INTERFACE mode
pfc no-drop queues queue-range
For the dot1p-queue assignments, refer to the dot1p Priority-Queue Assignment table.
The maximum number of lossless queues globally supported on the switch is two.
The range is from 0 to 7. Separate the queue values with a comma; specify a priority range with a
dash; for example, pfc no-drop queues 1,7 or pfc no-drop queues 2-7.
The default: No lossless queues are configured.
NOTE: Dell Networking OS Behavior: By default, no lossless queues are configured on a port.
A limit of two lossless queues is supported on a port. If the amount of priority traffic that you configure to
be paused exceeds the two lossless queues, an error message displays.
In S6000, any pfc-dot1p priorities configured on a given interface need not be the same across the
system. In other words, lossless queue limit is applicable on a per-port level and not on the global-config
context. For example, one of the Te/Fo interfaces can have pfc-dot1p priorities as 2 and 3. Whereas, the
other Te/Fo interface(s) can have its pfc-dot1p priorities as 4 and 5.
It is the user responsibility to have symmetric PFC configurations on the interfaces involved in a particular
PFC-enabled traffic-flow to obtain lossless behavior.
Configuring PFC in a DCB Map
An S6000–ON switch supports the use of a DCB map in which you configure priority-based flow control
(PFC) setting. To configure PFC parameters, you must apply a DCB map on an S6000–ON interface. This
functionality is supported on the S6000–ON platform.

PFC Configuration Notes

PFC provides flow control based on the 802.1p priorities in a converged Ethernet traffic that is received
on an interface and is enabled by default when you enable DCB. As an enhancement to the existing
Ethernet pause functionality, PFC stops traffic transmission for specified priorities (CoS values) without
impacting other priority classes. Different traffic types are assigned to different priority classes.
When traffic congestion occurs, PFC sends a pause frame to a peer device with the CoS priority values of
the traffic that needs to be stopped. DCBx provides the link-level exchange of PFC parameters between
peer devices. PFC allows network administrators to create zero-loss links for SAN traffic that requires no-
drop service, while at the same time retaining packet-drop congestion management for LAN traffic.
Data Center Bridging (DCB) 255